A prospective study of 383 patients with suspected ectopic pregnancy was carried out at Yale-New Haven Hospital to determine the value of adnexal sonographic findings in the diagnosis of ectopic pregnancy. In patients with adnexal sonographic results and human chorionic gonadotropin titers less than 6000 mIU/ml (n = 220), the presence of a noncystic mass had a positive predictive value of 83%, and the presence of a cystic mass had a positive predictive value of 35%. The combination of a noncystic mass and fluid in the cul-de-sac (found in 22% of all patients with ectopic gestations) was the best predictor of an ectopic pregnancy with a 94% positive predictive value. It is suggested that the demonstration of a non-cystic mass, alone or in the presence of fluid in the cul-de-sac, be used as an indication for diagnostic laparoscopy.