743uterine activity (Alexandria units) at varying doses of orciprenaline in seven patients studied for this effect is given in Table II. Tachyphylaxis was not observed in the three patients studied for 25, 70, and Maternal tachycardia and increase in pulse pressure were noted in all patients but presented no problems. The most unpleasant side effect was nausea and vomiting which occurred in three patients at the effective dose after 9, 20, and 22 minutes respectively. This may well limit the period of administration. Further clinical experience has shown that diazepam reduces this distressing symptom.Some difficulty was encountered in recording the fetal heart rate phonocardiographically at higher infusion rates. This was due to the transmission of abdominal aortic sounds when the maternal pulse pressure was markedly increased. The maternal aortic sounds then obscured the fetal heart sounds so that the maternal pulse rate was recorded instead. In these circumstances the fetal heart rate was auscultated in the usul manner without difficulty.