Background: Magnetic resonance (MR)-based T2 relaxation time measurement is a sensitive technique to detect neuropathological changes such as intramyelinic edema in vivo. Objective: To determine whether vigabatrin (VGB) causes an increase in T2 relaxation time in patients with newly diagnosed localization-related epilepsy over I year. Methods: Patients with newly diagnosed localization-related epilepsy who participated in a VGB-carbamazepine (CBZ) monotherapy trial were included. All were scanned on a 1.5 T Siemens SP63 Magnetom scanner. T2 maps of the brain were obtained at baseline and at follow-up 1 year later. Nine control subjects had repeated hippocampal T2 maps with a median interval of approximate to 2 years. Results: 23 patients (12 on VGB and II on CBZ) were included. There were no increased T2 relaxation times in the VGB treated group at follow-up and no significant differences between the two antiepileptic drug groups. There was a rend for the temporal and frontal white matter T2 relaxation times to be lower on follow-up in the patients compared to the control subjects. Conclusion: The findings do not suggest that intramyelinic edema occurs in patients taking monotherapy VGB for 1 year. (C) 1998 Elsevier Science B.V.