Accumulation of dodecylcyclohexane and eicosane is observed over a long period in rat fed a diet containing 0,1 p. 100 of these hydrocarbons. Carcass retention of the amounts ingested is of the order of 7 p. 100; preferential fixation occurs in adipose tissue. Almost linear accumulation is observed as long as carcass lipids continue to increase. If hydrocarbon administration is discontinued, mobilization is slow since only 2/3 of the amount stored disappears in 4 months. Finally, if the animals are fed an energy-restricted diet, mobilization of stored hydrocarbons, although more pronounced, occurs at a lower rate than stored lipid mobilization.