diff --git a/TODO.md b/TODO.md
index adebf6b..b538191 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,5 +1,6 @@
 # TODO
 
 ## Fixes
+- [x] Fix CSV import UNIQUE constraint crash: skip rows whose identifier already exists in DB
 - [x] Fix wrong `require_once` depth in `public/admin/actions/page.php` (`../../` → `../../../`)
 - [x] Fix same path depth bug in `formulaire.php` and `publish.php`
diff --git a/public/admin/import.php b/public/admin/import.php
index 237ed8f..e6da398 100644
--- a/public/admin/import.php
+++ b/public/admin/import.php
@@ -168,6 +168,18 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_FILES['csv_file'])) {
                         $finalityId = $rowFin ? $rowFin['id'] : null;
                     }
 
+                    // Skip if identifier already exists
+                    if (!empty($identifier)) {
+                        $stmtCheck = $pdo->prepare("SELECT id FROM theses WHERE identifier = ?");
+                        $stmtCheck->execute([$identifier]);
+                        if ($stmtCheck->fetch()) {
+                            $db->rollback();
+                            $skippedCount++;
+                            $importResults[] = "⚠ Ligne $lineNumber: identifiant \"$identifier\" déjà présent, ignoré.";
+                            continue;
+                        }
+                    }
+
                     // Insert thesis
                     $stmt = $pdo->prepare("
                         INSERT INTO theses (