In 15 out of 39 patients (38.5 %) with therapy resistant epilepsies, vigabatrin add on led to an at least 50 % improvement of seizure frequency. The effectiveness was best in focal epilepsies. A loss of this effect was observed in 3 patients and in seven patients the treatment had to be discontinued - in spite of good therapeutic effect - because of severe side effects. These were especially observed in patients with proven brain lesions. Psychotic events only occured during the initial dosage finding phase. The long term follow-up (up to 64 months) showed a 50 to 100 % improvement in 12 out of 39 patients (30.8 %).