Acute and chronic alcohol intoxication may lead to various types of corpuscular hemolytic anemias, irrespective of other coexisting organ damage such as liver cirrhosis. It also suppresses hemopoiesis in the bone marrow, leading to hyporegenerative anemia and to a pathogenetically unclear red cell macrocytosis, which in turn represents a sensitive and valuable index for occult alcoholism. Alcohol also suppresses platelet production. Acute intoxication may, furthermore, lead to reversible thrombocytopenia due to platelet sequestration. Platelet function is affected by alcohol both in vitro and in vivo, the defect being similar to that provoked by aspirin. The impaired host defense in chronic alcoholism is not yet adequately explained. It appears to be based on depression of bone marrow granulocyte reserve, granulocyte mobilization and granulocyte function, and also on impressive functional abnormalities of the lympho-plasmocellular system. The clinical relevance of alcohol-mediated hematological changes has not yet been sufficiently defined. It is certainly underestimated.