diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/common/Registry.java b/navalplanner-business/src/main/java/org/navalplanner/business/common/Registry.java
index 2afbf8583..8edd2d41a 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/common/Registry.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/common/Registry.java
@@ -28,6 +28,7 @@ import org.navalplanner.business.labels.daos.ILabelDAO;
 import org.navalplanner.business.labels.daos.ILabelTypeDAO;
 import org.navalplanner.business.materials.daos.IMaterialCategoryDAO;
 import org.navalplanner.business.materials.daos.IMaterialDAO;
+import org.navalplanner.business.orders.daos.IHoursGroupDAO;
 import org.navalplanner.business.orders.daos.IOrderElementDAO;
 import org.navalplanner.business.qualityforms.daos.IQualityFormDAO;
 import org.navalplanner.business.resources.daos.ICriterionDAO;
@@ -112,6 +113,9 @@ public class Registry {
     @Autowired
     private ICriterionDAO criterionDAO;
 
+    @Autowired
+    private IHoursGroupDAO hoursGroupDAO;
+
     private Registry() {
     }
 
@@ -190,4 +194,8 @@ public class Registry {
         return getInstance().criterionDAO;
     }
 
+    public static IHoursGroupDAO getHoursGroupDAO() {
+        return getInstance().hoursGroupDAO;
+    }
+
 }
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java
index 4a5c01970..fa371652f 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java
@@ -20,11 +20,16 @@
 
 package org.navalplanner.business.orders.daos;
 
+import org.hibernate.Criteria;
+import org.hibernate.criterion.Restrictions;
 import org.navalplanner.business.common.daos.GenericDAOHibernate;
+import org.navalplanner.business.common.exceptions.InstanceNotFoundException;
 import org.navalplanner.business.orders.entities.HoursGroup;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.context.annotation.Scope;
 import org.springframework.stereotype.Repository;
+import org.springframework.transaction.annotation.Propagation;
+import org.springframework.transaction.annotation.Transactional;
 
 /**
  * Dao for {@link HoursGroup}
@@ -35,4 +40,45 @@ import org.springframework.stereotype.Repository;
 @Scope(BeanDefinition.SCOPE_SINGLETON)
 public class HoursGroupDAO extends GenericDAOHibernate<HoursGroup, Long>
         implements IHoursGroupDAO {
-}
+
+    @Override
+    @Transactional(readOnly = true, propagation = Propagation.REQUIRES_NEW)
+    public boolean existsByCodeAnotherTransaction(HoursGroup hoursGroup) {
+        return existsByCode(hoursGroup);
+    }
+
+    private boolean existsByCode(HoursGroup hoursGroup) {
+        try {
+            HoursGroup result = findUniqueByCode(hoursGroup);
+            return result != null && result != hoursGroup;
+        } catch (InstanceNotFoundException e) {
+            return false;
+        }
+    }
+
+    @Override
+    @Transactional(readOnly = true, propagation = Propagation.REQUIRES_NEW)
+    public HoursGroup findUniqueByCodeAnotherTransaction(HoursGroup hoursGroup)
+            throws InstanceNotFoundException {
+        return findUniqueByCode(hoursGroup);
+    }
+
+    private HoursGroup findUniqueByCode(HoursGroup hoursGroup)
+            throws InstanceNotFoundException {
+        if ((hoursGroup == null) || (hoursGroup.getCode() == null)) {
+            return null;
+        }
+
+        Criteria c = getSession().createCriteria(HoursGroup.class);
+        c.add(Restrictions.eq("code", hoursGroup.getCode()));
+
+        HoursGroup result = (HoursGroup) c.uniqueResult();
+        if (result == null) {
+            throw new InstanceNotFoundException(hoursGroup.getCode(),
+                    HoursGroup.class.getName());
+        } else {
+            return result;
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/IHoursGroupDAO.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/IHoursGroupDAO.java
index c8cd347d9..e4abdcbba 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/IHoursGroupDAO.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/IHoursGroupDAO.java
@@ -21,6 +21,7 @@
 package org.navalplanner.business.orders.daos;
 
 import org.navalplanner.business.common.daos.IGenericDAO;
+import org.navalplanner.business.common.exceptions.InstanceNotFoundException;
 import org.navalplanner.business.orders.entities.HoursGroup;
 
 /**
@@ -30,4 +31,9 @@ import org.navalplanner.business.orders.entities.HoursGroup;
  */
 public interface IHoursGroupDAO extends IGenericDAO<HoursGroup, Long> {
 
+    boolean existsByCodeAnotherTransaction(HoursGroup hoursGroup);
+
+    HoursGroup findUniqueByCodeAnotherTransaction(HoursGroup hoursGroup)
+            throws InstanceNotFoundException;
+
 }
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java
index b6a26759a..5258c936a 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/HoursGroup.java
@@ -26,10 +26,14 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
 
+import org.hibernate.validator.AssertTrue;
 import org.hibernate.validator.NotEmpty;
 import org.hibernate.validator.NotNull;
 import org.hibernate.validator.Valid;
 import org.navalplanner.business.common.BaseEntity;
+import org.navalplanner.business.common.Registry;
+import org.navalplanner.business.common.exceptions.InstanceNotFoundException;
+import org.navalplanner.business.orders.daos.IHoursGroupDAO;
 import org.navalplanner.business.requirements.entities.CriterionRequirement;
 import org.navalplanner.business.requirements.entities.DirectCriterionRequirement;
 import org.navalplanner.business.requirements.entities.IndirectCriterionRequirement;
@@ -275,4 +279,21 @@ public class HoursGroup extends BaseEntity implements Cloneable,
         return false;
     }
 
+    @AssertTrue(message = "code is already being used")
+    public boolean checkConstraintUniqueCode() {
+        IHoursGroupDAO hoursGroupDAO = Registry.getHoursGroupDAO();
+
+        if (isNewObject()) {
+            return !hoursGroupDAO.existsByCodeAnotherTransaction(this);
+        } else {
+            try {
+                HoursGroup hoursGroup = hoursGroupDAO
+                        .findUniqueByCodeAnotherTransaction(this);
+                return hoursGroup.getId().equals(getId());
+            } catch (InstanceNotFoundException e) {
+                return true;
+            }
+        }
+    }
+
 }