ACKNOWLEDGMENT The authors are indebted to R. R. Race for a sample of anti-Kell serum. With the aid of this specimen, it was possible to identify another antibody (anti-Lazarus) studied in our laboratory since 1946 as of the Kell variety. This patient had two stillbirths due to hemolytic disease of the fetus and one surviving child who is Kell or Lazarus negative, the husband being heterozygous (cf. "controls" in table 1). The authors are also indebted to Mr Benson Rosenberg, Elizabeth, N. J., for the blood specimens of the Kul. family, and to Dr. W. E. Hoffman, Charleston, W. Va., for the Mc. family. The tests with anti-Kell were made with the aid of Coombs anti-human serum. Identical results with anti-Lazarus serum were obtained using both the Coombs technic and albumin suspended cells. The test with anti-Cellano were made with saline suspended cells.