There is a major need for a mouse model of Gaucher disease, but the glucocerebrosidase knockout mouse is not viable; it dies shortly before or immediately after birth, apparently because of involvement of the central nervous system and/or skin. The most common form of Gaucher disease, type I, has a phenotype that is limited to the monocyte-macrophage system. We have created a chimeric mouse by infusing hematopoietic stem cells from fetuses that are homozygous for the glucocerebrosidase knockout into irradiated mice. The chimeric mice manifested a severe deficiency of glucocerebrosidase activity in peripheral blood cells and spleen indicating a lack of cell-cell correction. Levels of glucocerebroside in spleen and liver are increased, and infusing the mice with exogenous glucocerebroside/albumin particles produced a marked increase in the amount of glucocerebroside stored in liver and spleen. Morphologically identifiable Gaucher cells were not present. The chimeric model reflects the increased glycolipid storage in the reticuloendothelial system that is characteristic of Gaucher disease, and could be useful as a model for studying treatment of Gaucher disease.