1. Bovine albumin solution as a testing and diluting medium was used for the detection of abnormal iso-antibodies in the serum of various cases of hemolytic anemia.
2. Five patients with idiopathic acquired hemolytic anemia all showed a warm agglutinin, although in 4 of these patients antibody could not be detected by use of the standard saline technic. Higher titres than in salt sDlution were always obtained in the albumin medium. Three patients with congenital spherocytic anemia not in crisis, 2 patients with severe Mediterranean anemia, and 2 with sickle cell anemia failed to show antibody. In the crisis of 1 case of congenital spherocytic anemia an autohemolysin was temporarily found with the use of bovine albumin. Other cases of acquired hemolytic anemia (chemical, symptomatic, hypersplenic) failed to show antibody. Detection of antibody was of distinct value in the diagnosis of acquired hemolytic anemia of the "idiopathic" type. Its continued presence in such a case after splenectomy rendered the prognosis doubtful.
3. In the further differentiation of various types of familial and acquired cases, use was made of the red cell survival time. Parallel determinations of the survival time and of iso-antibodies showed a distinct correlation. Use of the anti-human globulin rabbit serum test to detect iso-antibody adsorbed to the red cell is cited as of further diagnostic aid.