An open randomized comparative study was carried out on the efficacy and tolerance of carbamazepine--Tegretol CR (CBZ) and sodium valproate--Depakine chrono (VPA) in adult patients with newly diagnosed epilepsy with partial complex seizures with or without secondary generalization. The trial included 60 patients aged 18-50 years. Thirty patients were randomized to an initial CBZ dose of 2 x 200 mg daily, and the remaining 30 patients to an initial VPA dose of 2 x 300 mg daily. The follow-up was carried out for 3 years. If clinically necessary, the doses were increased while monitoring blood serum drug levels until the therapeutic effect was achieved or side effects developed. A maximum dose of CBZ was established at 2000 mg/day, and that of VPA at 3000 mg/day. Within the first 6 months of the therapy, 5 patients on CBZ (16.6%) and 2 patients on VPA (6.6%) were excluded from the trial due to poor seizure control or adverse side effects. Between the seventh month and the end of the third year of the study, the number of patients additionally excluded for the above reasons was 5 (16.6%) individuals on CBZ and 6 (20%) patients on VPA. Out of the patients who were followed up for 3 years, 16 (80%) on CBZ and 16 (72.7%) on VPA achieved 12-month remission, while 12 patients on CBZ (60%) and 13 (59%) on VPA achieved a 24-month remission. It can be thus concluded, that the patients administered CBZ achieved the remission faster than the patients on VPA, but after 3-year therapy the effectiveness of the two drugs was comparable. There was no difference in effectiveness between patients with partial complex seizures with and without secondary generalization. The number of patients with adverse effects in both groups was comparable.