In a case of Farber's disease, lysosomal inclusions were shown to contain lamellar, rectilinear, or curvilinear material. In tissue culture, when fibroblasts from the patient were overloaded with ceramides containing nonhydroxylated fatty acids a lysosomal accumulation of small curvilinear structures identical with those observed at autopsy were seen. These inclusions persisted for several weeks after the cells were replaced in a normal culture medium. Normal fibroblasts overloaded in the same experimental conditions showed identical, although less numerous, lysosomal inclusions, which disappeared rapidly in a ceramide-free culture medium. No inclusions were found after overloading normal or pathologic fibroblasts with ceramides containing hydroxylated fatty acids.