I am looking for this 80s or 90s movie.The movie was about a man who was attacked by a maniac and while he was unconscious his kidney was removed/stolen. The victim was trying to find the maniac who took his kidney in order to get his revenge. I remember there was a scene where a group of 5-6 people were gathered with a psychologist and talking about their problems, and on his turn the victim told them his story, took his shirt off and showed them the wound from the surgery of the kidney.

Hi Marija - not an exact match to your description, but possibly this?

The Donor (1995) - IMDb (http://www.imdb.com/title/tt0112886/)
The Donor - Rotten Tomatoes (http://www.rottentomatoes.com/m/donor/trailers/10900495)