diff --git a/app/Service/DeletionService.php b/app/Service/DeletionService.php
index 2cee272f..872e4996 100644
--- a/app/Service/DeletionService.php
+++ b/app/Service/DeletionService.php
@@ -11,6 +11,7 @@ use App\Models\Client;
 use App\Models\Member;
 use App\Models\Organization;
 use App\Models\OrganizationInvitation;
+use App\Models\Passport\RefreshToken;
 use App\Models\Project;
 use App\Models\ProjectMember;
 use App\Models\Report;
@@ -169,6 +170,10 @@ class DeletionService
             }
         }
 
+        // Refresh tokens are not linked to the user directly, so they need to be deleted via their access tokens.
+        // Otherwise a still-valid refresh token could be used to issue a new access token for a deleted user,
+        // which fails with a foreign key violation on oauth_access_tokens.user_id.
+        RefreshToken::query()->whereIn('access_token_id', $user->accessTokens()->pluck('id'))->delete();
         $user->accessTokens()->delete();
         $user->authCodes()->delete();
 
diff --git a/tests/Unit/Service/DeletionServiceTest.php b/tests/Unit/Service/DeletionServiceTest.php
index b9dd4d56..30b4ccc9 100644
--- a/tests/Unit/Service/DeletionServiceTest.php
+++ b/tests/Unit/Service/DeletionServiceTest.php
@@ -10,6 +10,9 @@ use App\Exceptions\Api\CanNotDeleteUserWhoIsOwnerOfOrganizationWithMultipleMembe
 use App\Models\Client;
 use App\Models\Member;
 use App\Models\Organization;
+use App\Models\Passport\Client as PassportClient;
+use App\Models\Passport\RefreshToken;
+use App\Models\Passport\Token;
 use App\Models\Project;
 use App\Models\ProjectMember;
 use App\Models\Report;
@@ -23,6 +26,7 @@ use Illuminate\Support\Collection;
 use Illuminate\Support\Facades\Event;
 use Illuminate\Support\Facades\Log;
 use Illuminate\Support\Facades\Storage;
+use Illuminate\Support\Str;
 use PHPUnit\Framework\Attributes\CoversClass;
 use Tests\TestCaseWithDatabase;
 use TiMacDonald\Log\LogEntry;
@@ -424,4 +428,45 @@ class DeletionServiceTest extends TestCaseWithDatabase
             'role' => Role::Placeholder->value,
         ]);
     }
+
+    public function test_delete_user_deletes_access_tokens_and_their_refresh_tokens_but_does_not_delete_tokens_of_other_users(): void
+    {
+        // Arrange
+        $user = User::factory()->create();
+        $otherUser = User::factory()->create();
+        $passportClient = PassportClient::factory()->create();
+
+        $userToken = Token::factory()->forUser($user)->forClient($passportClient)->create();
+        $userRefreshToken = RefreshToken::query()->create([
+            'id' => Str::random(100),
+            'access_token_id' => $userToken->getKey(),
+            'revoked' => false,
+            'expires_at' => now()->addDays(30),
+        ]);
+
+        $otherUserToken = Token::factory()->forUser($otherUser)->forClient($passportClient)->create();
+        $otherUserRefreshToken = RefreshToken::query()->create([
+            'id' => Str::random(100),
+            'access_token_id' => $otherUserToken->getKey(),
+            'revoked' => false,
+            'expires_at' => now()->addDays(30),
+        ]);
+
+        // Act
+        $this->deletionService->deleteUser($user);
+
+        // Assert
+        $this->assertDatabaseMissing(Token::class, [
+            'id' => $userToken->getKey(),
+        ]);
+        $this->assertDatabaseMissing(RefreshToken::class, [
+            'id' => $userRefreshToken->getKey(),
+        ]);
+        $this->assertDatabaseHas(Token::class, [
+            'id' => $otherUserToken->getKey(),
+        ]);
+        $this->assertDatabaseHas(RefreshToken::class, [
+            'id' => $otherUserRefreshToken->getKey(),
+        ]);
+    }
 }