In a prospective, randomized, double-blind study for the prevention of pregnancy-induced hypertension and preeclampsia, 41 primigravidae with positive roll-over test (28th-32nd week of pregnancy) received 80 mg aspirin/day or placebo until the end of the 37th week. In the patients treated with acetylsal-icylic acid (n = 22), 3 cases of proteinuria occurred, but no hypertensive pregnancy complication. In the placebo group (n = 19), 10 patients developed pregnancy-induced hypertension (6 of them preeclampsia). Group-specific differences concerning the occurrence of hypertension were statistically highly significant (p = 0.0004). No relevant differences were observed with regard to pregnancy duration, birth weight and umbilical artery pH value. The placebo group included 1 intrauterine death. No increased tendency to maternal or fetal bleeding was noticed.