diff --git a/thehive/app/org/thp/thehive/services/AlertSrv.scala b/thehive/app/org/thp/thehive/services/AlertSrv.scala
index f18809bd4f..fc6a60b5a2 100644
--- a/thehive/app/org/thp/thehive/services/AlertSrv.scala
+++ b/thehive/app/org/thp/thehive/services/AlertSrv.scala
@@ -7,7 +7,7 @@ import org.thp.scalligraph.query.PropertyUpdater
 import org.thp.scalligraph.services._
 import org.thp.scalligraph.traversal.TraversalOps._
 import org.thp.scalligraph.traversal.{Converter, IdentityConverter, StepLabel, Traversal}
-import org.thp.scalligraph.{CreateError, EntityId, EntityIdOrName, RichOptionTry, RichSeq}
+import org.thp.scalligraph.{BadRequestError, CreateError, EntityId, EntityIdOrName, RichOptionTry, RichSeq}
 import org.thp.thehive.controllers.v1.Conversion._
 import org.thp.thehive.dto.v1.InputCustomFieldValue
 import org.thp.thehive.models._
@@ -280,28 +280,31 @@ class AlertSrv @Inject() (
     } yield updatedCase
 
   def mergeInCase(alert: Alert with Entity, `case`: Case with Entity)(implicit graph: Graph, authContext: AuthContext): Try[Case with Entity] =
-    auditSrv
-      .mergeAudits {
-        // No audit for markAsRead and observables
-        // Audits for customFields, description and tags
-        val description = `case`.description + s"\n  \n#### Merged with alert #${alert.sourceRef} ${alert.title}\n\n${alert.description.trim}"
-        for {
-          _ <- markAsRead(alert._id)
-          _ <- importObservables(alert, `case`)
-          _ <- importCustomFields(alert, `case`)
-          _ <- caseSrv.addTags(`case`, get(alert).tags.toSeq.map(_.toString).toSet)
-          _ <- alertCaseSrv.create(AlertCase(), alert, `case`)
-          c <- caseSrv.get(`case`).update(_.description, description).getOrFail("Case")
-          details <- Success(
-            Json.obj(
-              "customFields" -> get(alert).richCustomFields.toSeq.map(_.toOutput.toJson),
-              "description"  -> c.description,
-              "tags"         -> caseSrv.get(`case`).tags.toSeq.map(_.toString)
+    if (get(alert).isImported)
+      Failure(BadRequestError("Alert is already imported"))
+    else
+      auditSrv
+        .mergeAudits {
+          // No audit for markAsRead and observables
+          // Audits for customFields, description and tags
+          val description = `case`.description + s"\n  \n#### Merged with alert #${alert.sourceRef} ${alert.title}\n\n${alert.description.trim}"
+          for {
+            _ <- markAsRead(alert._id)
+            _ <- importObservables(alert, `case`)
+            _ <- importCustomFields(alert, `case`)
+            _ <- caseSrv.addTags(`case`, get(alert).tags.toSeq.map(_.toString).toSet)
+            _ <- alertCaseSrv.create(AlertCase(), alert, `case`)
+            c <- caseSrv.get(`case`).update(_.description, description).getOrFail("Case")
+            details <- Success(
+              Json.obj(
+                "customFields" -> get(alert).richCustomFields.toSeq.map(_.toOutput.toJson),
+                "description"  -> c.description,
+                "tags"         -> caseSrv.get(`case`).tags.toSeq.map(_.toString)
+              )
             )
-          )
-        } yield details
-      }(details => auditSrv.alertToCase.merge(alert, `case`, Some(details)))
-      .flatMap(_ => caseSrv.getOrFail(`case`._id))
+          } yield details
+        }(details => auditSrv.alertToCase.merge(alert, `case`, Some(details)))
+        .flatMap(_ => caseSrv.getOrFail(`case`._id))
 
   def importObservables(alert: Alert with Entity, `case`: Case with Entity)(implicit
       graph: Graph,
@@ -400,6 +403,9 @@ object AlertOps {
     def imported: Traversal[Boolean, Boolean, IdentityConverter[Boolean]] =
       traversal.choose(_.outE[AlertCase], onTrue = true, onFalse = false)
 
+    def isImported: Boolean =
+      traversal.outE[AlertCase].exists
+
     def importDate: Traversal[Date, Date, Converter[Date, Date]] =
       traversal.outE[AlertCase].value(_._createdAt)