In comparing blood groupings and the Rh.D. factor in Negro schizophrenics with controls and with former findings, interesting differences were noted:1. Significant differences were found between schizophrenic subjects and control subjects in two of the three studies, one of which used Negro subjects and the other, white subjects.2. The Rh.D. factor rather than the blood group accounted for the differences between schizophrenics and normals in two of the studies.3. The Rh.D. factor operated differently in the Negro groups than in the white groups. Negro schizophrenics showed a greater proportion of Rh negative, and white schizophrenics showed a greater proportion of Rh positive.4. The Negro control group and the white control group had different distributions of the Rh.D. factor and of blood group characteristics; therefore, data from Negro and white subjects could not be appropriately combined.