Ectopic pregnancy (EP) is a common, life-threatening complication of pregnancy. Modern technology (ultrasonography and improved pregnancy tests) should facilitate the diagnosis of EP. However, in a retrospective review of 65 cases of confirmed EP managed over 18 months at an urban teaching hospital, only 37 of 65 patients (57%, Cl95 = 44%, 69%) received prompt diagnosis and treatment; delays occurred in 28 patients (43%). In 10 of the 27 delayed cases, the diagnosis of EP was not even considered at the time of the first visit. In patients with a delayed diagnosis, morbidity (transfusions, cardiovascular instability, progression of illness) did occur. Diagnostic pitfalls that resulted in delayed care were reviewed, delays most commonly occurred in patients with a benign examination or "atypical" pain. Risk factors for EP were missed (7 patients, 25%), subtle clues to blood loss were often ignored (10 patients, 36%), and passage of tissue was thought to exclude EP (2 patients). Ultrasound was only helpful for half of the diagnoses and was misinterpreted in 27%. A dry or serous culdocentesis occurred frequently. In five patients, a falling or low quantitative human chorionic gonadotropin level was believed to indicate a completed abortion. The authors conclude that almost half of EPs are still missed on the first physician visit; errors and pitfalls in diagnosis are still common in the 1980s.