1. In the present paper two cases of xanthelasmatosis (xanthoma) with marked changes in lipid and sterol metabolism are studied. 2. One of the cases without injuries shows accentuated cholester-oluria, while the other with renal injuries presented pyelonephritis without cholesteroluria. 3. Cholesterol, total fatty acids and lecithine give high values in both cases. Histo-chemical and polariscopic researches confirmed a real infiltration of cholesterol and lipids in tissues. 4. Burger's test in case I may be seen as a lack of tolerance to cholesterol. 5. Although insulin treatment decreased the cholesterol and glucose content of the blood in case I, it was not effective in relieving the clinical picture. In case II a reduction of cholesterol and glucose of the blood and a rapid desappearance of the growths was obtained. 6. Intradermal reaction with cholesterol in case I was positive, showing, therefore, a hypensensibilization, og the skin to infiltration substances. 7. Clinico-morphological aspects of the cases studies indicated a clear cutaneous sinsitisation. 8. Xanthelasmatosis (xanthoma) has been compared with toxic cutaneous diseases with be conclusion that the same methods must be adapted for the study of skin lipidosis as for toxidermic diseases.