The advanced modalities of vaginal ultrasonography and sensitive human chorionic gonadotropin assays have greatly facilitated the diagnosis of early ectopic pregnancy. The treatment spectrum for ectopic pregnancy ranges from a variety of conservative operative measures, including salpingectomy and operative laparoscopy, to various medical regimens or simply watchful observation alone. We report 12 cases in which the ectopic gestation was treated by transvaginal instillation of potassium chloride or methotrexate under sonographic guidance. Three of these, one of two patients receiving potassium chloride and two of six patients receiving methotrexate, later required a laparotomy. The level of beta-subunit of human chorionic gonadotropin was found to be unreliable in predicting the outcome in these patients. Ultrasound follow-up is mandatory. A protocol for treatment is presented.