During a ten-year period from 1969 through 1979, 22 of 1648 patients referred to the John I. Brewer Trophoblastic Disease Center of Northwestern University Medical School had repeat gestational trophoblastic disease, an incidence of 1.33%. A total of 52 trophoblastic disease episodes occurred in these 22 patients. Invasive mole or choriocarcinoma occurred as the first trophoblastic disease episode in only three patients (14%), whereas one of these sequelae was the second trophoblastic disease event in seven patients (32%). Seventeen patients (77%) had consecutive trophoblastic disease episodes. After a second trophoblastic disease episode, the risk for a subsequent event rose to 28%; however, 44% of these patients delivered viable infants. There was no difference in outcome of subsequent pregnancies with respect to previous chemotherapy.