A generalized erythematous scaly rash, alopecia, lymphadenopathy, and hepatosplenomegaly developed in an infant girl during the first 6 weeks of life. Repeated bacterial and fungal infections, persistent diarrhea, and generalized wasting complicated the course of her illness, and death occurred at 5 1/2 months of age. Lymph node architecture was completely obliterated by histiocytes and eosinophils; no plasma cells or germinal centers were present. Both humoral and cellular immune systems were severely but not completely impaired. Familial reticuloendotheliosis with eosinophilia is, in some cases, associated with combined immune deficiency.