Objective: To evaluate the success and safety of adenosine use in treating maternal supraventricular tachycardia (SVT) in pregnancy.Methods: Hemodynamically stable pregnant women diagnosed with supraventricular tachycardia admitted to Jackson Memorial hospital from 1990 to 1995 and treated with adenosine were included in the study. Adenosine was given intravenously with an initial dose of 6 mg, followed by two 12 mg doses as needed. Mothers and fetuses were followed prospectively to assess short-term and long-term effects of the treatment.Results: A total of four pregnant patients were treated with adenosine for medical cardioversion of SVT. All patients were hemodynamically stable upon arrival to the maternity ward and were successfully treated with adenosine. Both mothers and fetuses were monitored during treatment. Adenosine successfully converted the SVT to sinus rhythm, in all four patients. One patient was treated successfully twice, at 15 weeks and subsequently at 24 weeks. No complications occurred to either the mothers or the fetuses during the treatment. Five and ten minute APGAR scores at birth were greater than seven. Mothers and babies were followed from 1 month to 5 years after treatment and no contributory deleterious effects have been found. One patient was lost to follow-up.Conclusion: Our four patient cases, added to the limited published cases in the literature, support adenosine's safety and efficacy for the medical treatment of supraventricular tachycardia in the hemodynamically stable pregnant woman.