Carbamazepine was compared with phenytoin in a double-blind study. Of 87 patients, data on 70 patients were complete and used for analysis. Thirty-five patients were treated with each drug. The incidence of major side effects, minor side effects, and complete control (85%) was the same in both groups. A mild but significant elevation of WBC count was found before initiation of drug treatment in the patients presenting with generalized convulsive seizures. Sporadically, elevations in SGOT and LDH were seen; WBC counts below 4,000 were reported, but these were not clinically significant.