Studies made during the last 20 years indicate that in mixed, but predominantly [SEE TABLE VI IN PDF SOURCE] Caucasian, racial groups, birth defect occurs in approximately 1 to 4% of all live births. To supplement the scanty information on the incidence of birth defects among North American Negro children the birth records were reviewed for a ten-year period at two hospitals in the District of Columbia. Approximately 60% of all Negro children born in the District of Columbia are delivered in these hospitals. Among these children representing a cross section of the socioeconomic groups of the Negro community, the incidence of birth defects was approximately 6%. There were significant differences in the frequencies at the two hospitals, the hospital with the largest number of births from mothers in the lower socioeconomic group had approximately three times as many defects as the hospital utilized by the higher socioeconomic group. The ten congenital malformations occurring most frequently in a group of predominantly Caucasian Boston children were compared with the ten commonest defects in the District of Columbia group. Six defects, namely, polydactyly, clubfoot, hypospadias, congenital heart disease, mongolism, and cleft palate were among the commonest ten in both groups; the frequencies of these varied. The five congenital malformations occurring most frequently at the two hospitals in the District of Columbia were similar in type and in incidence. Multiple defects were rare in both racial groups and no grouping of defects seemed to occur together more frequently than others.