In a socio-economically stable community with free access to medical care, a prospective comparison was made of pregnancy, delivery and neonatal data concerning 480 grand multiparas (> or = 5 deliveries) and 325 controls. The mean diastolic blood pressure was slightly higher (79.8 vs. 77.8 mmHg) among the grand multiparas and the rates of episiotomy differed greatly (5.8% in the grand multiparas vs. 45.7% in the controls). The main clinical difference was a slightly higher incidence of placental complications-i.e., praevia, abruptio and retentio (3.4% vs. 0.9%; P < 0.05) in the grand multiparas. The differences had no effect on neonatal outcome. Grand multiparity should be regarded as an obstetrical risk factor, mainly because of the higher frequency of placental complications. With good obstetric care there should be no adverse effects on the mother or the newborn.