Female weanling rats were chronically centrifuged at 4.15 g with controls at terrestrial gravity. Samples of 6 to 10 rats were sacrificed for body composition studies at 0, 28, 63, 105, 179 and 308 days of centrifugation and 57 days after centrifugation ended. The centrifuged group had a significantly lower mature body mass than the controls (251 vs 318 g) but the rate of approach to the mature values was the same in both groups. Retirement to 1 g on the 60th day resulted in complete recovery. Masses of muscle, bone, skin, CNS, heart, kidneys, body water and body fat were changed in the centrifuged group. However, an analysis of the growth in mass of individual components relative to growth of the total fat-free compartment revealed that only skin (which increased in mass) was responding to centrifugation per se.