1. A cell is described in the bone marrow aspirates of two patients which has not previously been fully described. This is a large reticuloendothelial-like cell filled with blue-staining granules. This cell has been found in successive bone marrow films aspirated from sternum and iliac crest. 2. These cells were also found in a splenic aspiration from one of the patients and were compared to similar cells from a case summarized by Möschlin. 3. The case reports show striking clinical similarities in the two patients, i.e. hepatosplenomegaly in relatively symptom-free individuals. This suggests that a common syndrome is present. 4. Differential histochemical studies of the granular material in the cytoplasm are reported. 5. The significance and function of these unusual cells in the marrow is unknown.