The amounts and the distribution of the various lipids were studied in the sciatic nerves from normal and trembler mice. When compared to the normal, the total lipidic amount was reduced by 66% in the trembler mouse, and each class of lipid was decreased nearly the same way, except for the cholesterol esters the value of which increased five times. The level of each individual phospholipid was decreased, phosphatidylcholine being the least affected and phosphatidylserine the most altered.