154 pregnancies of 140 epileptic patients were observed in a prospective study. The number of seizures during pregnancy and 3 first puerperal months was compared with the number of seizures during the 12 months preceeding pregnancy. An increase in the number of seizures was noticed in 32% of the cases, a decrease in 14% and unchanged frequency in 23% of the cases, 31% being seizure-free during the study period. The highest incidence of major convulsive seizures occurred during the last trimester of pregnancy, while the incidcnce of complex partial seizures was highest during puerperium. No factors were found which may predict the increase in seizures.