A rapid, selective and sensitive isocratic reversed-phase HPLC method for the simultaneous determination of oxcarbazepine, its main metabolites (mono and dihydroxycarbazepine), lamotrigine, carbamazepine and carbamazepine-epoxide in plasma samples has been implemented. Analytes were extracted on solid-phase cartridges (SPE) and chromatographic separation was achieved on a Zorbax SB-CN column. The chromatographic peak area ratio based on UV absorbency at 214 nm was used for quantitative analysis. This HPLC method has been successfully used for routine evaluation to monitor plasma concentrations in epileptic patients affering to our institute and for pharmacokinetic studies regarding patients cotreated with drugs inducing or inhibiting OXC metabolism.