diff --git a/app/ApiModule/Services/ScheduleService.php b/app/ApiModule/Services/ScheduleService.php
index e6cff2961..72131bf17 100644
--- a/app/ApiModule/Services/ScheduleService.php
+++ b/app/ApiModule/Services/ScheduleService.php
@@ -218,10 +218,20 @@ public function saveProgram(ProgramSaveDto $programSaveDto) : ResponseDto
         $start     = $programSaveDto->getStart();
         $end       = $start->add(new DateInterval('PT' . $block->getDuration() . 'M'));
 
+        $overlappingLecturersProgram = false;
+        foreach ($block->getLectors() as $lector) {
+            if ($this->userRepository->hasOverlappingLecturersProgram($lector, $programId, $start, $end)) {
+                $overlappingLecturersProgram = true;
+                break;
+            }
+        }
+
         if (! $this->user->isAllowed(SrsResource::PROGRAM, Permission::MANAGE_SCHEDULE)) {
             $responseDto->setMessage($this->translator->translate('common.api.schedule_user_not_allowed_manage'));
         } elseif (! $this->settingsService->getBoolValue(Settings::IS_ALLOWED_MODIFY_SCHEDULE)) {
             $responseDto->setMessage($this->translator->translate('common.api.schedule_not_allowed_modfify'));
+        } elseif ($overlappingLecturersProgram) {
+            $responseDto->setMessage($this->translator->translate('common.api.schedule_lector_has_another_program'));
         } elseif ($room && $this->roomRepository->hasOverlappingProgram($room, $programId, $start, $end)) {
             $responseDto->setMessage($this->translator->translate('common.api.schedule_room_occupied', null, ['name' => $room->getName()]));
         } elseif ($block->getMandatory() === ProgramMandatoryType::AUTO_REGISTERED && $this->programRepository->hasOverlappingProgram($programId, $start, $end)) {
diff --git a/app/Model/User/UserRepository.php b/app/Model/User/UserRepository.php
index ad77903d6..074786e38 100644
--- a/app/Model/User/UserRepository.php
+++ b/app/Model/User/UserRepository.php
@@ -8,6 +8,7 @@
 use App\Model\Acl\Role;
 use App\Model\Enums\ApplicationState;
 use App\Model\Program\Block;
+use DateTimeImmutable;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\Common\Collections\Criteria;
@@ -278,6 +279,29 @@ public function getLectorsOptions() : array
         return $options;
     }
 
+    /**
+     * Má lektor jiný program ve stejný čas?
+     */
+    public function hasOverlappingLecturersProgram(User $lector, ?int $programId, DateTimeImmutable $start, DateTimeImmutable $end) : bool
+    {
+        $qb = $this->createQueryBuilder('u')
+            ->select('u.id')
+            ->join('u.lecturersBlocks', 'b')
+            ->join('b.programs', 'p')
+            ->where($this->createQueryBuilder('u')->expr()->orX(
+                "(p.start < :end) AND (DATE_ADD(p.start, (b.duration * 60), 'second') > :start)",
+                "(p.start < :end) AND (:start < (DATE_ADD(p.start, (b.duration * 60), 'second')))"
+            ))
+            ->andWhere('u.id = :uid')
+            ->andWhere('(p.id != :pid) or (:pid IS NULL)')
+            ->setParameter('start', $start)
+            ->setParameter('end', $end)
+            ->setParameter('uid', $lector->getId())
+            ->setParameter('pid', $programId);
+
+        return ! empty($qb->getQuery()->getResult());
+    }
+
     /**
      * Uloží uživatele.
      *
diff --git a/app/lang/common.cs_CZ.neon b/app/lang/common.cs_CZ.neon
index 5b05bc83a..1644dd733 100644
--- a/app/lang/common.cs_CZ.neon
+++ b/app/lang/common.cs_CZ.neon
@@ -151,6 +151,7 @@ api:
     program_registered: "Program byl úspěšně přihlášen."
     schedule_program_not_registered: "Na tento program jste nebyli přihlášeni."
     program_unregistered: "Program byl úspěšně odhlášen."
+    schedule_lector_has_another_program: "Lektor má v tuto dobu již jiný program."
     schedule_room_occupied: "Místnost \"%name%\" je v tuto dobu již obsazena."
     schedule_auto_registered_not_allowed: "Automaticky přihlašovaný program nesmí být ve stejnou dobu jako jiný program."