diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index fb899c702..3e197efaf 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -393,7 +393,11 @@ impl Dialog {
                     Text { key: "header", label: "Header (&L left, &C center, &R right; &P page, &N pages, &D date, &A sheet):" },
                     Text { key: "footer", label: "Footer:" },
                 ],
-                json!({"header": "", "footer": "&CPage &P of &N"}),
+                {
+                    let sheet = app.session.active().and_then(|d| d.wb.active());
+                    let (header, footer) = sheet.map(|s| (s.print.header.clone(), s.print.footer.clone())).unwrap_or_default();
+                    json!({"header": header, "footer": footer})
+                },
             ),
             "pageSetup" => {
                 // Opens on the active sheet's saved margins, so OK without edits rewrites them unchanged.
diff --git a/crates/ui-egui/tests/interaction.rs b/crates/ui-egui/tests/interaction.rs
index 02084ffb8..80fe04395 100644
--- a/crates/ui-egui/tests/interaction.rs
+++ b/crates/ui-egui/tests/interaction.rs
@@ -911,3 +911,21 @@ fn undo_after_backspace_restores_the_cleared_cell() {
     assert_eq!(value(&h, "A1"), Value::Number(3200.0));
     assert_eq!(value(&h, "C5"), Value::Number(11750.0));
 }
+
+#[test]
+fn header_footer_dialog_opens_on_the_saved_header_and_footer() {
+    // #523: the dialog started from a fixed empty header and `&CPage &P of &N`, so OK replaced the sheet's text.
+    let mut s = blank();
+    s.execute("pageLayout.headerFooter", json!({"header": "&LLeft", "footer": "&CConfidential"})).unwrap();
+    let mut h = harness(s);
+    h.state_mut().open_dialog("headerFooter", json!({}));
+    h.run_steps(2);
+    let d = h.state_mut().dialog.as_mut().unwrap();
+    assert_eq!(d.values["header"], json!("&LLeft"));
+    assert_eq!(d.values["footer"], json!("&CConfidential"));
+    d.values.insert("header".into(), json!("&CNew"));
+    let vals = json!(d.values.clone());
+    h.state_mut().run("pageLayout.headerFooter", vals).unwrap();
+    let pr = &h.state().session.active().unwrap().wb.active().unwrap().print;
+    assert_eq!((pr.header.as_str(), pr.footer.as_str()), ("&CNew", "&CConfidential"));
+}