Of 14 patients with a history of partial epilepsy who received vigabatrin 2 g daily for 6 months, eight were newly diagnosed and received vigabatrin as monotherapy, while the remaining six received vigabatrin in addition to pre-existing treatment with phenobarbitone. Neurophysiological and neuropsychological evaluations, done before and after the therapeutic period, included the Luria-Nebraska neuropsychological battery (LNNB), electroencephalograms (EEGs) and evoked potentials. The results for each item of the test battery at baseline were compared with those after 6 months' treatment. There were no statistically significant differences on the functional scales of the LNNB, the EEG or the evoked potentials. There was a significant improvement (P = 0.01) in the LNNB topographic scales for the right frontal lobe and the motor-sensory area following treatment. These results indicate that vigabatrin has no detrimental effects on cognitive function and may improve function.