The bone marrow scans with colloidal 198Au were performed on 33cases with hematologically normal patients and patients with various blood dyscrasia. Bone marrow aspirations were done at iliac crest in all cases but one. A correlation between the scan findings and an erythroid cellularity was evaluated. The following results were obtained. 1) Out of 33 cases, 23 (about 70%) showed a correlation between 198Au marrow uptakes on the scans and the erythroid cellularity. 2) The diseases in which no correlation existed between 198Au uptake and erythroid cellularity were aplastic anemia, acute leukemia and chronic myelogenous leukemia.