We evaluated the pregnancy outcome of all patients with elevations of both maternal serum alpha-fetoprotein and human chorionic gonadotropin since institution of combined serum screening at our program. After analysis of 34,404 samples, 99 patients were found to have significant elevations of both maternal serum alpha-fetoprotein and human chorionic gonadotropin. The ultrasound findings, amniocentesis results, and pregnancy outcomes were determined in each case. Sixty-six patients with singleton gestations met entry criteria. Pregnancy outcome information is available for 63 of these patients, 60% of whom had at least one complication. Thirty-three patients with multiple gestations met inclusion criteria. Pregnancy outcome information is available for 31 of these, 81% of whom had at least one complication. These patients had a high incidence of pregnancy related complications. This group would appear to be at higher risk than women with elevation of either maternal serum alpha-fetoprotein or human chorionic gonadotropin alone.