diff --git a/anatomy/forms.py b/anatomy/forms.py
index 7cc962ad..c7795d87 100644
--- a/anatomy/forms.py
+++ b/anatomy/forms.py
@@ -290,4 +290,19 @@ class ExamGroupsForm(ExamGroupsFormMixin):
 class SuggestIncorrectAnswerForm(ModelForm):
     class Meta:
         model = AnatomyQuestion
-        fields = ["answer_suggest_incorrect"]
\ No newline at end of file
+        fields = ["answer_suggest_incorrect"]
+
+
+class PrimaryAnswerForm(Form):
+    existing_answer = ChoiceField(required=False, choices=[], label="Use existing answer")
+    new_answer = CharField(required=False, widget=Textarea(attrs={"rows":3}), label="Or create new primary answer")
+
+    def __init__(self, *args, **kwargs):
+        question = kwargs.pop("question", None)
+        super().__init__(*args, **kwargs)
+        choices = [("", "-- choose existing --")]
+        if question is not None:
+            # Only include existing non-proposed CORRECT answers, ordered by answer text
+            for a in question.answers.filter(proposed=False, status=Answer.MarkOptions.CORRECT).order_by('answer'):
+                choices.append((str(a.pk), a.answer))
+        self.fields["existing_answer"].choices = choices
\ No newline at end of file
diff --git a/anatomy/templates/anatomy/partials/primary_answer_display.html b/anatomy/templates/anatomy/partials/primary_answer_display.html
new file mode 100644
index 00000000..06767f8e
--- /dev/null
+++ b/anatomy/templates/anatomy/partials/primary_answer_display.html
@@ -0,0 +1,25 @@
+<div id="primary-answer-container" class="position-relative primary-answer-wrap py-1">
+    <strong>{{ question.get_primary_answer }}</strong>
+    <button
+        class="edit-primary-btn btn btn-sm btn-link text-muted position-absolute"
+        style="right:0; top:0;"
+        hx-get="{% url 'anatomy:primary_answer_htmx' pk=question.pk %}"
+        hx-target="#primary-answer-container"
+        hx-swap="outerHTML"
+        aria-label="Edit primary answer"
+    >
+        Edit
+    </button>
+
+    <style>
+    /* Scoped styles for primary answer edit control */
+    .primary-answer-wrap .edit-primary-btn {
+        opacity: 0.55;
+        transition: opacity 120ms ease, color 120ms ease;
+    }
+    .primary-answer-wrap:hover .edit-primary-btn {
+        opacity: 1;
+        color: inherit;
+    }
+    </style>
+</div>
diff --git a/anatomy/templates/anatomy/partials/primary_answer_empty.html b/anatomy/templates/anatomy/partials/primary_answer_empty.html
new file mode 100644
index 00000000..4b8bbd3f
--- /dev/null
+++ b/anatomy/templates/anatomy/partials/primary_answer_empty.html
@@ -0,0 +1,4 @@
+<div id="primary-answer-container">
+    <span class="small text-muted">No primary answer set</span>
+    <button class="btn btn-sm btn-link" hx-get="{% url 'anatomy:primary_answer_htmx' pk=question.pk %}" hx-target="#primary-answer-container" hx-swap="outerHTML">Add primary answer</button>
+</div>
diff --git a/anatomy/templates/anatomy/partials/primary_answer_form.html b/anatomy/templates/anatomy/partials/primary_answer_form.html
new file mode 100644
index 00000000..37c7e9a5
--- /dev/null
+++ b/anatomy/templates/anatomy/partials/primary_answer_form.html
@@ -0,0 +1,58 @@
+{% load crispy_forms_tags %}
+<div id="primary-answer-container">
+    <form hx-post="{% url 'anatomy:primary_answer_htmx' pk=question.pk %}" hx-target="#primary-answer-container" hx-swap="outerHTML">
+        {% csrf_token %}
+        <div class="mb-2">
+            <label for="id_existing_answer" class="form-label">Select existing answer</label>
+                <select name="existing_answer" id="id_existing_answer" class="form-select">
+                {% for val, text in form.existing_answer.field.choices %}
+                    <option value="{{ val }}" {% if val == form.initial.existing_answer %}selected{% endif %}>{{ text }}</option>
+                {% endfor %}
+            </select>
+        </div>
+
+        <div class="mb-2">
+            <label for="id_new_answer" class="form-label">Or add a new primary answer</label>
+            <textarea name="new_answer" id="id_new_answer" class="form-control" rows="3"></textarea>
+
+    <script>
+    (function(){
+        const sel = document.getElementById('id_existing_answer');
+        const ta = document.getElementById('id_new_answer');
+        if(!sel || !ta) return;
+
+        function update() {
+            try {
+                if (ta.value && ta.value.trim().length > 0) {
+                    sel.disabled = true;
+                } else {
+                    sel.disabled = false;
+                }
+            } catch(e) {
+                // ignore
+            }
+        }
+
+        // initial state
+        update();
+
+        // listeners
+        sel.addEventListener('change', function(){
+            if(this.value && this.value !== '') {
+                ta.disabled = true;
+            } else {
+                ta.disabled = false;
+            }
+        });
+
+        ta.addEventListener('input', update);
+    })();
+    </script>
+        </div>
+
+        <div class="d-flex gap-2">
+            <button class="btn btn-primary btn-sm" type="submit">Save primary answer</button>
+            <button class="btn btn-secondary btn-sm" type="button" hx-get="{% url 'anatomy:primary_answer_htmx' pk=question.pk %}?cancel=1" hx-target="#primary-answer-container" hx-swap="outerHTML">Cancel</button>
+        </div>
+    </form>
+</div>
diff --git a/anatomy/templates/anatomy/question_detail.html b/anatomy/templates/anatomy/question_detail.html
index 8c0ec686..4c6bcd91 100644
--- a/anatomy/templates/anatomy/question_detail.html
+++ b/anatomy/templates/anatomy/question_detail.html
@@ -36,7 +36,11 @@
                     </div>
 
                     <h6 class="mt-2">Primary answer</h6>
-                    <div class="mb-2"><strong>{{ question.get_primary_answer }}</strong></div>
+                    {% if question.primary_answer %}
+                        {% include 'anatomy/partials/primary_answer_display.html' %}
+                    {% else %}
+                        <div id="primary-answer-container" hx-get="{% url 'anatomy:primary_answer_htmx' pk=question.pk %}" hx-trigger="load" hx-swap="outerHTML"></div>
+                    {% endif %}
 
                     <h6>Answers</h6>
                     <details class="mb-3">
diff --git a/anatomy/urls.py b/anatomy/urls.py
index 793ff6d5..22cf7c1f 100644
--- a/anatomy/urls.py
+++ b/anatomy/urls.py
@@ -114,6 +114,7 @@ urlpatterns = [
     path("exam/<int:exam_pk>/<int:sk>/mark2/exam_marked", views.mark2_exam_marked, name="mark2_exam_marked"),
     path("question/<int:pk>/mark2/question_marked", views.mark2_question_marked, name="mark2_question_marked"),
     path("exam/mark2/edit_answer", views.mark2_edit_answer, name="mark2_edit_answer"),
+    path("question/<int:pk>/primary_answer/", views.primary_answer_htmx, name="primary_answer_htmx"),
 ]
 
 urlpatterns.extend(generic_view_urls(views.GenericViews))
diff --git a/anatomy/views.py b/anatomy/views.py
index 388dd9b9..ba752c58 100644
--- a/anatomy/views.py
+++ b/anatomy/views.py
@@ -46,6 +46,7 @@ from .forms import (
     AnatomyQuestionForm,
     ExamForm,
     SuggestIncorrectAnswerForm,
+    PrimaryAnswerForm,
 )
 from .models import (
     AnatomyQuestion,
@@ -1655,4 +1656,58 @@ def question_add_exam(request, question_id: int):
             return HttpResponse(mark_safe(html))
 
 
-    raise PermissionDenied()
\ No newline at end of file
+    raise PermissionDenied()
+
+
+@login_required
+def primary_answer_htmx(request, pk: int):
+    """HTMX endpoint to render or update a question's primary answer.
+
+    GET: render the form for selecting/creating primary answer.
+    POST: create/select answer and set `question.primary_answer`, then
+    return the display fragment.
+    """
+    if not request.htmx:
+        raise PermissionDenied()
+
+    question = get_object_or_404(AnatomyQuestion, pk=pk)
+
+    if not question.can_edit(request.user):
+        return HttpResponse("Invalid permissions", status=403)
+
+    if request.method == "POST":
+        form = PrimaryAnswerForm(request.POST, question=question)
+        if form.is_valid():
+            new_text = form.cleaned_data.get("new_answer", "").strip()
+            existing = form.cleaned_data.get("existing_answer", "")
+
+            if new_text:
+                # create a new Answer and mark it CORRECT
+                ans = Answer(question=question, answer=new_text, proposed=False, status=Answer.MarkOptions.CORRECT)
+                ans.save()
+                question.primary_answer = ans
+                question.save(update_fields=["primary_answer"])
+            elif existing:
+                try:
+                    aid = int(existing)
+                    ans = Answer.objects.get(pk=aid, question=question)
+                    question.primary_answer = ans
+                    question.save(update_fields=["primary_answer"])
+                except (ValueError, Answer.DoesNotExist):
+                    return HttpResponse("Invalid answer choice", status=400)
+
+            # return display fragment
+            return render(request, "anatomy/partials/primary_answer_display.html", {"question": question})
+        else:
+            return HttpResponse("Invalid form", status=400)
+
+    # Handle cancel request to restore original state
+    if request.method == "GET" and request.GET.get("cancel"):
+        if question.primary_answer:
+            return render(request, "anatomy/partials/primary_answer_display.html", {"question": question})
+        else:
+            return render(request, "anatomy/partials/primary_answer_empty.html", {"question": question})
+
+    # GET - render form
+    form = PrimaryAnswerForm(question=question)
+    return render(request, "anatomy/partials/primary_answer_form.html", {"form": form, "question": question})
\ No newline at end of file