THE NONLIPID reticuloendothelioses are usually considered to include Hand-Schuller-Christian's disease, eosinophilic granuloma of the bone, and acute disseminated reticuloendotheliosis (Letterer-Siwe's disease). The latter is the least common of this group, approximately 41 cases having been previously reported. It is the purpose of this paper to contribute to the knowledge of this disease by reviewing the literature and reporting 15 additional cases. Our patients were 13 months or younger at the onset of the disease and illustrated classical features of acute disseminated reticuloendotheliosis. These characteristics included hepatosplenomegaly, anemia, skin lesions, adenopathy, bone lesions, and recurring secondary infections. With one exception all diagnoses were confirmed pathologically. HISTORICAL REVIEW The earliest reports of nonlipid reticuloendotheliosis concerned Hand-Schuller-Christian's disease. These were by Smith, 2 Hand, 3 Kay, 4 Schuller 5 and Christian 6 and resulted in characterization of the disease as a triad consisting of diabetes insipidus, exophthalmos, and defects in membranous bones. Epstein