The cases of 91 patients with congenital hemolytic anemia (H.a.) are reported. The causes of congenital H.a. and the laboratory test by which the diagnosis and precise subclassification of the disease were facilitated are indicated. Emphasis is placed on the therapeutic significance of splenectomy in those patients In whom laboratory tests with a radioactive marker [Cr 51]indicated that splenectomy could have a beneficial effect.