The disease most likely to be associated with large numbers of bone marrow storage histiocytes is Gaucher's disease. In our community of western Pennsylvania, eastern Ohio, and West Virginia, we have encountered 30 patients with Gaucher's disease during the past 25 years. During the same 25 years, a group of about 20 other patients have been examined for storage cells caused by diseases other than Gaucher's disease. These other conditions are associated with smaller numbers of storage cells, and these patients require a more extensive examination that should include serum or tissue lipid analyses, enzymology, and electron microscopy to assist in the diagnosis.