thanks for the reply; i update my EditPOST action method to:-

[HttpPost]
        public ActionResult Edit([Bind(Include = "Note,DoctorID,VisitID,StatusID,timestamp")] Visit visit) //[Bind(Include="Note,DoctorID,VisitID,StatusID")]
        {
            if ((visit.EditableByAssingedDoctor(User.Identity.Name)) || (visit.EditableByCreatedBy(User.Identity.Name)))
            {

                try
                {
                    if (ModelState.IsValid)
                    {

                        int id = visit.VisitID;
                        var v = repository.GetVisit(id);
                        visit.CreatedBy = v.CreatedBy;
                        visit.Date = v.Date;
                        visit.PatientID = v.PatientID;
                        visit.VisitTypeID = v.VisitTypeID;


                        repository.UpdateVisit(visit);
                        repository.Save();
                        return RedirectToAction("Index");
                    }
                }
                catch (DbUpdateConcurrencyException ex)
                {
//code goes here

and the repository.UpdateVisit(visit); code looks like:-

public void UpdateVisit(Visit v)
            {
                entities.Entry(v).State = EntityState.Modified;

            }

But when i run my application and i try to edit the visit object i got the following error :-

An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key.

on the repository.UpdateVisit(visit) Method; so what are going wrong? BR