A total of 234 oxytocin challenge tests (OCT, prenatal screening tests for placental insufficiency) were performed on 100 high-risk patients. The results were negative (N) in 68 of these 100 patients, suspicious (S) in 22 and positive (P) in 10. The incidence of late decelerations during labor was N, 5%; S, 40%; and P, 86%. Meconium staining of the amniotic fluid was N, 4%; S, 5%; and P, 30%. The cesarean section rate was N, 16%; S, 36%; and P, 60%. Of these, the cesarean section rate for fetal indications was N, 9%; S, 25%; and P, 67%. The overall perinatal mortality in the study group was 2% (N, 1.5%; S, 0%; P, 10%). The negative OCT appears innocuous and positive OCT as the most ominous. The majority of patients with positive OCT may be delivered vaginally without endangering the fetus if fetal scalp blood pH determinations can be performed.