Bilateral breast stimulation was used to evoke a spontaneous contraction stress test. The success rate and incidence of abnormal uterine activity using the stimulus was compared with patients tested by the authors' standard oxytocin stress test protocol. Bilateral breast stimulation was initially used for 346 tests between 32 and 43 weeks of gestational age. A satisfactory test, or three contractions within ten minutes, was obtained in 239 (69%) patients. The testing time was reduced with successful breast stimulation. The incidence of abnormal uterine activity after breast stimulation was not statistically different from that observed with oxytocin administration alone. However, when oxytocin was administered after breast stimulation, there was a significant increase in the incidence of prolonged contractions.