Three patients presented with histiocytic medullary reticulosis. A review of 49 additional patients allowed an evaluation of the hematological aspects of this disease. Hemolytic anemia, granulocytopenia, and thrombocytopenia commonly observed in this disorder may result from excessive phagocytosis of blood cells by abnormal histiocytes within medullary centers of bone and lymphoid tissue. In addition, these histiocytes may serve as a repository for sequestered erythrocytic iron and cholesterol.