A 35-year-old Ashkenazi woman with Gaucher's disease was evaluated for persistent thrombocytopenia. The diagnosis of Gaucher's disease was made by bone marrow aspiration and confirmed by the determination of glucocerebrosidase levels in leukocytes and cultured skin fibroblasts. Studies of platelet-associated IgG and in vivo platelet survival demonstrated immune-mediated destruction of platelets consistent with immune thrombocytopenic purpura. A trial of prednisone had no effect on the platelet count. Total splenectomy resulted in a complete and prolonged remission. The clinical implications of Gaucher's disease and concurrent immune thrombocytopenic purpura are discussed.