Maternal serum α-fetoprotein levels are higher in black women. Misinterpretation of maternal serum α-fetoprotein screening results can subject black gravid women to unnecessary invasive diagnostic procedures and their calculable risks. Screening errors for black women can result from the use of normative data bases established with maternal serum samples drawn from other racial groups or the use of such data bases in conjunction with a published correction factor. Because the incidence of open neural tube defects is lower for blacks than for others, excessive false positive results for blacks (estimated to be 8817 to 28,215 cases annually) would be a pernicious misapplication of maternal serum α-fetoprotein screening. We address the problem outlined above and recommend independently developed, valid, normative data bases.