Glycolipid changes in spleen autopsy specimens were determined in four cases of Gaucher's disease type I, three cases of type II, and twelve cases of type III. These changes were also determined in liver autopsy specimens from three cases of type II and in nine cases of type III. The concentration of glucosylceramide in spleen was of the same magnitude in all three types, 36.3 ±11.7 mmol/ kg in type I, 32.7 ± 8.5 mmol/ kg in type II, and 32.6 ± 6.9 mmol/ kg in type III. In liver there were large differences in the glucosylceramide concentration between splenectomized and non-splenectomized cases. Thus, in the non-splenectomized type III cases it was 9.9 ± 3.0 mmol/ kg, while in the splenectomized type III cases it was 24.1 ± 6.1 mmol/ kg. The accelerated deposition of glucosylceramide in liver after splenectomy was also demonstrated by analyses of liver biopsy specimens. A 2–6-fold increase of gangliosides was found in liver and spleen from the three types, with no significant differences between the types. The increase of gangliosides was limited almost exclusively to GM3. Glucosylsphingosine, never detected in normal tissue, was demonstrated in all samples from Gaucher's livers and spleens. The concentration in spleen was in type II, 0.16 ± 0.05 mmol/ kg, in type III, 0.19 ± 0.05 mmol/ kg, while in type I it was significantly lower, 0.07 ±0.03 mmol/ kg. In liver, the highest concentrations occurred in the splenectomized type III subjects, 0.16 ± 0.08 mmol/ kg, while in the nonsplenectomized type III cases it was 0.06 ± 0.02 mmol/ kg and in type II 0.09 ±0.02 mmol/ kg. The demonstration of high concentrations of the cytotoxic compound glycosylsphingosine may be a contributing factor behind the tissue necrosis and fibrosis commonly seen in spleens and livers from Gaucher's patients.