diff --git a/src/api/structures/__tests__/identifiers.test.js b/src/api/structures/__tests__/identifiers.test.js
index 33b51980..c76bfe13 100644
--- a/src/api/structures/__tests__/identifiers.test.js
+++ b/src/api/structures/__tests__/identifiers.test.js
@@ -1,7 +1,9 @@
-import { structures as resource, identifiers as subresource } from '../../resources';
+import {
+  structures as resource,
+  identifiers as subresource,
+} from '../../resources';
 
 let authorization;
-let id;
 let resourceId;
 
 const payload = {
@@ -25,20 +27,16 @@ beforeAll(async () => {
   resourceId = body.id;
 });
 
-beforeEach(async () => {
+afterEach(async () => {
+  // Delete all structures identifiers
   const { body } = await global.superapp
-    .post(`/${resource}/${resourceId}/${subresource}`)
-    .set('Authorization', authorization)
-    .send(payload);
-  id = body.id;
-});
+    .get(`/${resource}/${resourceId}/${subresource}`)
+    .set('Authorization', authorization);
+  const promises = body.data.map((identifier) => global.superapp
+    .delete(`/${resource}/${resourceId}/${subresource}/${identifier.id}`)
+    .set('Authorization', authorization));
 
-afterEach(async () => {
-  if (id) {
-    await global.superapp
-      .delete(`/${resource}/${resourceId}/${subresource}/${id}`)
-      .set('Authorization', authorization);
-  }
+  await Promise.all(promises);
 });
 
 describe('API > structures > identifiers > create', () => {
@@ -77,17 +75,38 @@ describe('API > structures > identifiers > create', () => {
       .send(rest)
       .expect(400);
   });
+
+  it('should return 204 if an identifier with same type and same value already exists', async () => {
+    const paylod = { type: 'siret', value: '12345678912346' };
+
+    await global.superapp
+      .post(`/${resource}/${resourceId}/${subresource}`)
+      .set('Authorization', authorization)
+      .send(paylod)
+      .expect(201);
+
+    await global.superapp
+      .post(`/${resource}/${resourceId}/${subresource}`)
+      .set('Authorization', authorization)
+      .send(paylod)
+      .expect(204);
+  });
 });
 
 describe('API > structures > identifiers > update', () => {
   it('should update an existing identifier', async () => {
+    const { body: { id } } = await global.superapp
+      .post(`/${resource}/${resourceId}/${subresource}`)
+      .set('Authorization', authorization)
+      .send(payload);
+
     const type = 'wikidata';
-    const { body } = await global.superapp
+    const { body: updatedBody } = await global.superapp
       .patch(`/${resource}/${resourceId}/${subresource}/${id}`)
       .set('Authorization', authorization)
       .send({ type })
       .expect(200);
-    expect(body.type).toBe(type);
+    expect(updatedBody.type).toBe(type);
   });
 
   it('should throw bad request if id too short', async () => {
@@ -107,6 +126,11 @@ describe('API > structures > identifiers > update', () => {
   });
 
   it('should throw bad request with badly formatted payload', async () => {
+    const { body: { id } } = await global.superapp
+      .post(`/${resource}/${resourceId}/${subresource}`)
+      .set('Authorization', authorization)
+      .send(payload);
+
     await global.superapp
       .patch(`/${resource}/${resourceId}/${subresource}/${id}`)
       .set('Authorization', authorization)
@@ -115,6 +139,11 @@ describe('API > structures > identifiers > update', () => {
   });
 
   it('should accept empty dates', async () => {
+    const { body: { id } } = await global.superapp
+      .post(`/${resource}/${resourceId}/${subresource}`)
+      .set('Authorization', authorization)
+      .send(payload);
+
     await global.superapp
       .patch(`/${resource}/${resourceId}/${subresource}/${id}`)
       .set('Authorization', authorization)
@@ -126,13 +155,19 @@ describe('API > structures > identifiers > update', () => {
 describe('API > structures > identifiers > read', () => {
   it('should read existing identifier', async () => {
     const { body } = await global.superapp
+      .post(`/${resource}/${resourceId}/${subresource}`)
+      .set('Authorization', authorization)
+      .send(payload);
+    const { id } = body;
+
+    const { body: readBody } = await global.superapp
       .get(`/${resource}/${resourceId}/${subresource}/${id}`)
       .set('Authorization', authorization)
       .expect(200);
-    expect(body.type).toBe(payload.type);
-    expect(body.value).toBe(payload.value);
-    expect(body.active).toBeFalsy();
-    expect(body.createdBy.lastName).toBe('user');
+    expect(readBody.type).toBe(payload.type);
+    expect(readBody.value).toBe(payload.value);
+    expect(readBody.active).toBeFalsy();
+    expect(readBody.createdBy.lastName).toBe('user');
   });
 
   it('should throw bad request if id too short', async () => {
@@ -166,6 +201,11 @@ describe('API > structures > identifiers > delete', () => {
   });
 
   it('should delete existing identifier', async () => {
+    const { body: { id } } = await global.superapp
+      .post(`/${resource}/${resourceId}/${subresource}`)
+      .set('Authorization', authorization)
+      .send(payload);
+
     await global.superapp
       .delete(`/${resource}/${resourceId}/${subresource}/${id}`)
       .set('Authorization', authorization)
@@ -207,14 +247,6 @@ describe('API > structures > identifiers > list', () => {
       });
   });
 
-  beforeEach(async () => {
-    if (id) {
-      await global.superapp
-        .delete(`/${resource}/${resourceId}/${subresource}/${id}`)
-        .set('Authorization', authorization);
-    }
-  });
-
   it('should list', async () => {
     const { body } = await global.superapp
       .get(`/${resource}/${resourceId}/${subresource}`)
diff --git a/src/api/structures/identifiers/identifiers.middlewares.js b/src/api/structures/identifiers/identifiers.middlewares.js
new file mode 100644
index 00000000..36728c47
--- /dev/null
+++ b/src/api/structures/identifiers/identifiers.middlewares.js
@@ -0,0 +1,8 @@
+import { identifiersRepository } from '../../commons/repositories';
+
+export const validateStructureIdentifierCreatePayload = async (req, res, next) => {
+  const { type, value } = req.body;
+  const { resourceId } = req.params;
+  const check = await identifiersRepository.findOne({ resourceId, type, value });
+  return check ? res.status(204).json() : next();
+};
diff --git a/src/api/structures/identifiers/identifiers.routes.js b/src/api/structures/identifiers/identifiers.routes.js
index 967698f6..81730b6d 100644
--- a/src/api/structures/identifiers/identifiers.routes.js
+++ b/src/api/structures/identifiers/identifiers.routes.js
@@ -6,7 +6,8 @@ import { saveInElastic, saveInStore } from '../../commons/middlewares/event.midd
 import { readQuery, readQueryWithLookup } from '../../commons/queries/identifiers.query';
 import elasticQuery from '../../commons/queries/structures.elastic';
 import { identifiersRepository as repository, structuresRepository } from '../../commons/repositories';
-import { identifiers as subresource, structures as resource } from '../../resources';
+import { structures as resource, identifiers as subresource } from '../../resources';
+import { validateStructureIdentifierCreatePayload } from './identifiers.middlewares';
 
 const router = new express.Router();
 
@@ -14,6 +15,7 @@ router.route(`/${resource}/:resourceId/${subresource}`)
   .get(controllers.list(repository, readQuery))
   .post([
     createContext,
+    validateStructureIdentifierCreatePayload,
     setGeneratedInternalIdInContext(subresource),
     controllers.create(repository, readQueryWithLookup),
     saveInStore(subresource),
diff --git a/src/openapi/paths/structures/identifiers.yml b/src/openapi/paths/structures/identifiers.yml
index 7849b1f4..8216cfcc 100644
--- a/src/openapi/paths/structures/identifiers.yml
+++ b/src/openapi/paths/structures/identifiers.yml
@@ -57,6 +57,8 @@ collectionMethods:
           application/json:
             schema:
               $ref: '../../api.yml#/components/schemas/StructureIdentifier'
+      '204':
+        description: 'No content'
       '400':
         $ref: '../../api.yml#/components/responses/BadRequest'
       '401':