diff --git a/atlas/templates/atlas/new_uploads.html b/atlas/templates/atlas/new_uploads.html
index 7f168fc5..ff32d7d6 100644
--- a/atlas/templates/atlas/new_uploads.html
+++ b/atlas/templates/atlas/new_uploads.html
@@ -74,6 +74,11 @@
         </button>
     </div>
 
+    <details id="ocr-debug-panel" class="mb-3">
+        <summary class="fw-semibold">OCR Debug Panel</summary>
+        <div id="ocr-debug-content" class="small text-muted mt-2">OCR has not run yet.</div>
+    </details>
+
     <div class="alert alert-warning d-none anon-alert" role="alert">
         <p class="mb-2">Potential anonymisation issues were detected. Flagged series are highlighted below.</p>
         <div id="anon-issue-summary" class="small"></div>
@@ -181,6 +186,7 @@
             duplicateSeriesUrls: new Set(),
             forceAnonymisationOverride: false,
             ocrWorker: null,
+            ocrDebug: null,
             currentTagsRecord: null,
             duplicateCheckInProgress: false,
             duplicateCheckRunId: 0,
@@ -223,6 +229,67 @@
             return div.innerHTML;
         }
 
+        function resetOcrDebug(status = "idle", message = "OCR has not run yet.") {
+            window.uploadPreview.ocrDebug = {
+                status,
+                message,
+                totalSamples: 0,
+                processedSamples: 0,
+                flaggedSeriesCount: 0,
+                entries: [],
+                updatedAt: new Date().toISOString(),
+            };
+            renderOcrDebugPanel();
+        }
+
+        function renderOcrDebugPanel() {
+            const root = document.getElementById("ocr-debug-content");
+            if (!root) return;
+
+            const debug = window.uploadPreview.ocrDebug;
+            if (!debug) {
+                root.innerHTML = "OCR has not run yet.";
+                return;
+            }
+
+            const sampleRows = debug.entries.slice(-30).map((entry) => {
+                const reasons = entry.reasons?.length ? escapeHtml(entry.reasons.join(", ")) : "No PHI pattern matched";
+                return `
+                    <tr>
+                        <td>${escapeHtml(entry.seriesUid)}</td>
+                        <td>${escapeHtml(entry.path)}</td>
+                        <td>${entry.flagged ? '<span class="text-warning fw-semibold">Flagged</span>' : '<span class="text-success">Clear</span>'}</td>
+                        <td>${reasons}</td>
+                        <td><code>${escapeHtml(entry.preview)}</code></td>
+                    </tr>
+                `;
+            }).join("");
+
+            root.innerHTML = `
+                <div class="mb-2">
+                    <strong>Status:</strong> ${escapeHtml(debug.status)}<br>
+                    <strong>Message:</strong> ${escapeHtml(debug.message)}<br>
+                    <strong>Samples:</strong> ${debug.processedSamples}/${debug.totalSamples} · <strong>Flagged series:</strong> ${debug.flaggedSeriesCount}
+                </div>
+                ${sampleRows ? `
+                    <div class="table-responsive ocr-debug-table-wrap">
+                        <table class="table table-sm align-middle ocr-debug-table">
+                            <thead>
+                                <tr>
+                                    <th>Series UID</th>
+                                    <th>File</th>
+                                    <th>Result</th>
+                                    <th>Match reasons</th>
+                                    <th>OCR preview</th>
+                                </tr>
+                            </thead>
+                            <tbody>${sampleRows}</tbody>
+                        </table>
+                    </div>
+                ` : ""}
+            `;
+        }
+
         async function parseDicomMetadata(file) {
             try {
                 const buffer = await file.arrayBuffer();
@@ -664,19 +731,34 @@
             return window.uploadPreview.ocrWorker;
         }
 
-        function detectOcrPhi(text) {
+        function getOcrPhiReasons(text) {
             const value = (text || "").toLowerCase();
+            const reasons = [];
 
             // Catch common clinical identifier markers and identifier-like tokens.
-            if (value.includes("accession") || value.includes("patient") || value.includes("nhs") || value.includes("hospital")) {
-                return true;
-            }
+            if (value.includes("accession")) reasons.push("contains 'accession'");
+            if (value.includes("patient")) reasons.push("contains 'patient'");
+            if (value.includes("nhs")) reasons.push("contains 'nhs'");
+            if (value.includes("hospital")) reasons.push("contains 'hospital'");
+
+            if (/(ref|rk9|rh8|ra9|rbz|rba)\d+/i.test(value)) reasons.push("site prefix + number pattern");
+            if (/\b\d{3}[\s-]?\d{3}[\s-]?\d{4}\b/.test(value)) reasons.push("10-digit grouped number pattern");
+            if (/\b\d{10}\b/.test(value)) reasons.push("10-digit number pattern");
+            if (/\b\d{6,8}\b/.test(value)) reasons.push("6-8 digit number pattern");
+            if (/\b(?:dob|d\.o\.b|birth|born)\b/.test(value)) reasons.push("date-of-birth keyword");
+
+            return reasons;
+        }
+
+        function detectOcrPhi(text) {
+            return getOcrPhiReasons(text).length > 0;
+        }
 
             return /(ref|rk9|rh8|ra9|rbz|rba)\d+/i.test(value)
-                || /\b\d{3}[\s-]?\d{3}[\s-]?\d{4}\b/.test(value)
-                || /\b\d{10}\b/.test(value)
-                || /\b\d{6,8}\b/.test(value)
-                || /\b(?:dob|d\.o\.b|birth|born)\b/.test(value);
+            || /\b\d{3}[\s-]?\d{3}[\s-]?\d{4}\b/.test(value)
+            || /\b\d{10}\b/.test(value)
+            || /\b\d{6,8}\b/.test(value)
+            || /\b(?:dob|d\.o\.b|birth|born)\b/.test(value);
         }
 
         function buildOcrSamples(records) {
@@ -755,17 +837,33 @@
         async function runOcrChecks() {
             if (!document.getElementById("check-anonymisation-ocr").checked) {
                 window.uploadPreview.records.forEach(r => { r.ocrWarning = false; });
+                resetOcrDebug("disabled", "OCR check is disabled in Upload Settings.");
                 return;
             }
 
             if (!window.Tesseract || typeof window.Tesseract.createWorker !== "function") {
                 window.uploadPreview.records.forEach(r => { r.ocrWarning = false; });
+                resetOcrDebug("error", "OCR engine is unavailable in this browser session.");
                 toastr.error("OCR engine is unavailable in this browser session.");
                 return;
             }
 
             const samples = buildOcrSamples(window.uploadPreview.records);
-            if (!samples.length) return;
+            if (!samples.length) {
+                resetOcrDebug("idle", "No included files available for OCR sampling.");
+                return;
+            }
+
+            window.uploadPreview.ocrDebug = {
+                status: "running",
+                message: "OCR checks in progress.",
+                totalSamples: samples.length,
+                processedSamples: 0,
+                flaggedSeriesCount: 0,
+                entries: [],
+                updatedAt: new Date().toISOString(),
+            };
+            renderOcrDebugPanel();
 
             const worker = await ensureOcrWorker();
             let index = 0;
@@ -778,17 +876,46 @@
                     const blob = await getDownscaledOcrBlob(record.file);
                     const result = await worker.recognize(blob);
                     const text = result?.data?.text || "";
-                    if (detectOcrPhi(text)) {
+                    const reasons = getOcrPhiReasons(text);
+                    const flagged = reasons.length > 0;
+                    if (flagged) {
                         flaggedSeriesUids.add(record.seriesUid);
                     }
+
+                    const preview = text.replace(/\s+/g, " ").trim().slice(0, 180);
+                    window.uploadPreview.ocrDebug.entries.push({
+                        seriesUid: record.seriesUid,
+                        path: record.path,
+                        flagged,
+                        reasons,
+                        preview,
+                    });
                 } catch (err) {
                     // Ignore per-image OCR errors and continue with other samples.
+                    window.uploadPreview.ocrDebug.entries.push({
+                        seriesUid: record.seriesUid,
+                        path: record.path,
+                        flagged: false,
+                        reasons: ["OCR error"],
+                        preview: String(err?.message || "OCR failed"),
+                    });
+                } finally {
+                    window.uploadPreview.ocrDebug.processedSamples = index;
+                    window.uploadPreview.ocrDebug.flaggedSeriesCount = flaggedSeriesUids.size;
+                    window.uploadPreview.ocrDebug.updatedAt = new Date().toISOString();
+                    renderOcrDebugPanel();
                 }
             }
 
             window.uploadPreview.records.forEach((record) => {
                 record.ocrWarning = record.include && flaggedSeriesUids.has(record.seriesUid);
             });
+
+            window.uploadPreview.ocrDebug.status = "complete";
+            window.uploadPreview.ocrDebug.message = `OCR complete. ${flaggedSeriesUids.size} series flagged from ${samples.length} sampled image(s).`;
+            window.uploadPreview.ocrDebug.flaggedSeriesCount = flaggedSeriesUids.size;
+            window.uploadPreview.ocrDebug.updatedAt = new Date().toISOString();
+            renderOcrDebugPanel();
         }
 
         async function calculateBlake3Hash(file) {
@@ -985,6 +1112,7 @@
 
             window.uploadPreview.forceAnonymisationOverride = false;
             resetUploadResults();
+            resetOcrDebug();
 
             window.uploadPreview.records.forEach((r) => {
                 if (r.objectUrl) URL.revokeObjectURL(r.objectUrl);
@@ -1296,6 +1424,8 @@
                 return;
             }
 
+            resetOcrDebug();
+
             document.addEventListener("click", async function (e) {
                 const includeSeries = e.target.closest(".include-series");
                 if (includeSeries) {
@@ -1494,5 +1624,22 @@
         .table-warning th {
             color: #ffc107;
         }
+
+        #ocr-debug-panel {
+            border: 1px solid rgba(255, 255, 255, 0.08);
+            border-radius: 8px;
+            padding: 8px 10px;
+            background: rgba(255, 255, 255, 0.02);
+        }
+
+        .ocr-debug-table-wrap {
+            max-height: 320px;
+        }
+
+        .ocr-debug-table code {
+            white-space: pre-wrap;
+            word-break: break-word;
+            font-size: 0.75rem;
+        }
     </style>
 {% endblock %}