diff --git a/internal/handlers/handlers.go b/internal/handlers/handlers.go
index 2530c7d..516d7a1 100644
--- a/internal/handlers/handlers.go
+++ b/internal/handlers/handlers.go
@@ -55,6 +55,7 @@ func (h *Handler) RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("GET /pulls", h.ListPulls)
 	mux.HandleFunc("GET /pulls/{owner}/{repo}/{index}", h.PullDetail)
 	mux.HandleFunc("POST /pulls/{owner}/{repo}/{index}/review", h.SubmitReview)
+	mux.HandleFunc("POST /pulls/{owner}/{repo}/{index}/state", h.SetPullState)
 
 	// Settings (handled separately for auth bypass).
 	settingsHandler := &SettingsHandler{
@@ -886,6 +887,53 @@ func (h *Handler) SetIssueState(w http.ResponseWriter, r *http.Request) {
 	http.Redirect(w, r, fmt.Sprintf("/issues/%s/%s/%d", owner, repo, index), http.StatusSeeOther)
 }
 
+// SetPullState handles POST /pulls/{owner}/{repo}/{index}/state.
+func (h *Handler) SetPullState(w http.ResponseWriter, r *http.Request) {
+	token := getToken(r)
+	owner := r.PathValue("owner")
+	repo := r.PathValue("repo")
+	indexStr := r.PathValue("index")
+
+	index, err := strconv.ParseInt(indexStr, 10, 64)
+	if err != nil {
+		http.Error(w, "invalid pull request index", http.StatusBadRequest)
+		return
+	}
+
+	if err := r.ParseForm(); err != nil {
+		http.Error(w, "bad request", http.StatusBadRequest)
+		return
+	}
+
+	state := r.FormValue("state")
+	if state != "open" && state != "closed" {
+		http.Error(w, "state must be 'open' or 'closed'", http.StatusBadRequest)
+		return
+	}
+
+	if err := h.Client.SetIssueState(r.Context(), token, owner, repo, index, state); err != nil {
+		slog.Error("failed to set pull request state", "error", err, "owner", owner, "repo", repo, "index", index, "state", state)
+		http.Error(w, "failed to update pull request state", http.StatusInternalServerError)
+		return
+	}
+
+	if isHTMX(r) {
+		w.Header().Set("Content-Type", "text/html; charset=utf-8")
+		if state == "closed" {
+			fmt.Fprintf(w, `<span class="state-closed" id="pull-state">closed</span>
+<button class="btn btn-secondary" hx-post="/pulls/%s/%s/%d/state" hx-vals='{"state":"open"}' hx-target="#state-section" hx-swap="innerHTML">Reopen PR</button>`,
+				template.HTMLEscapeString(owner), template.HTMLEscapeString(repo), index)
+		} else {
+			fmt.Fprintf(w, `<span class="state-open" id="pull-state">open</span>
+<button class="btn btn-danger" hx-post="/pulls/%s/%s/%d/state" hx-vals='{"state":"closed"}' hx-target="#state-section" hx-swap="innerHTML">Close PR</button>`,
+				template.HTMLEscapeString(owner), template.HTMLEscapeString(repo), index)
+		}
+		return
+	}
+
+	http.Redirect(w, r, fmt.Sprintf("/pulls/%s/%s/%d", owner, repo, index), http.StatusSeeOther)
+}
+
 // AddComment handles POST /issues/{owner}/{repo}/{index}/comment.
 func (h *Handler) AddComment(w http.ResponseWriter, r *http.Request) {
 	token := getToken(r)
diff --git a/internal/templates/pull_detail.html b/internal/templates/pull_detail.html
index 773675e..0d3aff8 100644
--- a/internal/templates/pull_detail.html
+++ b/internal/templates/pull_detail.html
@@ -4,7 +4,7 @@
 <div class="card">
   <div class="card-meta">
     <span class="type-badge type-pull">PR</span>
-    <span class="state-open">{{.Pull.State}}</span>
+    {{if eq .Pull.State "closed"}}<span class="state-closed">{{.Pull.State}}</span>{{else}}<span class="state-open">{{.Pull.State}}</span>{{end}}
     <span>{{.Pull.RepoOwner}}/{{.Pull.RepoName}} #{{.Pull.Number}}</span>
     {{range .Pull.Labels}}
     <span class="label" style="color:#{{.Color}};border:1px solid #{{.Color}}">{{.Name}}</span>
@@ -15,6 +15,17 @@
     <span class="diff-del">-{{.Pull.Deletions}}</span>
     {{if .Pull.Mergeable}}<span style="color:var(--accent-green);">Mergeable</span>{{end}}
   </div>
+  <div class="card-meta" style="margin-top:0.5rem;">
+    <span id="state-section">
+      {{if eq .Pull.State "closed"}}
+      <span class="state-closed" id="pull-state">{{.Pull.State}}</span>
+      <button class="btn btn-secondary" hx-post="/pulls/{{.Pull.RepoOwner}}/{{.Pull.RepoName}}/{{.Pull.Number}}/state" hx-vals='{"state":"open"}' hx-target="#state-section" hx-swap="innerHTML">Reopen PR</button>
+      {{else}}
+      <span class="state-open" id="pull-state">{{.Pull.State}}</span>
+      <button class="btn btn-danger" hx-post="/pulls/{{.Pull.RepoOwner}}/{{.Pull.RepoName}}/{{.Pull.Number}}/state" hx-vals='{"state":"closed"}' hx-target="#state-section" hx-swap="innerHTML">Close PR</button>
+      {{end}}
+    </span>
+  </div>
   {{if .RenderedBody}}
   <div class="card-body markdown-body">{{.RenderedBody}}</div>
   {{else if .Pull.Body}}