A simple and partially automated method for the HPLC determination of the new anticonvulsants vigabatrin and gabapentin in serum samples from epileptic patients is described. The first step in sample pre-treatment is the precipitation of the serum proteins using an excess of acetonitrile to which two internal standards have been added. After centrifugation the supernatant fraction of the samples was placed into an autosampler of an HPLC apparatus which can be programmed with different automatic procedures for pre-injection derivatizations.