The antepartum diagnosis of vasa previa has always been exceedingly difficult. A case report demonstrates the diagnostic value of hemoglobin electrophoresis on vaginal blood, a novel application of routine laboratory technique. Antepartum fetal monitoring (nonstress test [NST] and contraction stress test [CST]) in the presence of significant fetal anemia is of limited diagnostic value. The need for prompt neonatal care to salvage the compromised fetus is stressed.