Gaucher's disease is an uncommon metabolic disorder, which was first described by Gaucher in 1882, characterized by accumulation of distinctive Gaucher's cells in the reticuloendothelial system such as spleen, liver, and bone marrow. The great majority of cases have been reported in Jews, and others in negros and orientals. We are presenting two cases in homozygous twins in Korea, whose clinical manifestations are hepatosplenomegaly and bone lesions due to expansion of involved bones.