The authors describe 4 patients with grave aplastic anemia that developed after acute virus hepatitis. In two cases aplasia occurred at the icteric period of hepatitis, in one during convalescence, and in one 5 months after the recovery from hepatitis. The counter electrophoresis technique failed to reveal the Australian antigen in all the 4 cases. Ninety per cent of patients out of over 200 reported cases of aplastic anemia that developed after acute virus hepatitis died. Of the 4 cases followed up by the authors, 3 patients died. One of the female patients was subjected to splenectomy 3 weeks after the occurrence of grave aplasia with fatty bone marrow with a purpose of immunodepression. Splenectomy entailed a considerable decrease in hemorrhagic diathesis. Later on the patient was treated with caprine antilymphocytic globulin. At present the patient is in a state of remission. The problems of the pathogenesis of aplastic anemia following acute virus hepatitis and potentialities of the disease treatment are under discussion.