We evaluated the effectiveness of anticonvulsant drugs in 175 Nigerians of whom 106 were males, who suffer from epilepsy. The mean age at onset of seizures was 17.5 years and over 60% had seizures for more than one year before the commencement of therapy. Partial seizures were encountered in 98 (56%) subjects, and generalised seizures in 44%. One hundred and twenty six subjects were on single drug therapy and phenobarbital was the single most commonly prescribed agent. There was complete seizure control in 30 (17%), more than 50% control in another 87 (50%), and poor control in 58 (33%) of them. The factors associated with good control were infrequent seizures and monotherapy. The duration of seizure, and absence of aetiologic factor were not correlated with good control. There was no significant difference between phenobarbital and phenytoin effectiveness in seizure control. Adverse drug effects--mainly drowsiness and movement disorders--were encountered in 61 subjects. We conclude that the currently administered anticonvulsants are effective in 67% of the Nigerian patients studied and phenobarbital should remain a major drug because of economic considerations, availability and low side effects profile.