The authors reviewed changes in body weight in 44 patients treated with Gabapentin (GPN) for a period of 12 or more months. All patients had a seizure disorder and the dose of GPN was increased aiming at complete seizure control or until side effects limited further increase. Twenty-eight patients were receiving GPN dosages of > 3000 mg/day. Observed changes in body weight were as follows 10 patients gained more than 10% of their baseline weight, 15 patients gained 5% to 10% of baseline, 16 patients had no change, and 3 patients lost 5% to 10% of their initial weight. Weight increase started between the second and the third months of GPN treatment in most patients and tended to stabilize after 6 to 9 months of treatment, although the doses of GPN remained unchanged. Weight gain occurred in patients taking GPN in combination with each of the major antiepileptic drugs including Felbatol and also occurred with GPN monotherapy.