The concentrations of astaxanthin and $alpha$-tocopherol were measured from the muscle of the rainbow trout(Oncorhynchus mykiss) that had been fed the red yeast(Phaffia rhodozyma) containing 0.2% astaxanthin for 7, 14 and 21 days. The effect of the astaxanthin supplementation for 21 days on peroxidation of liver and muscle lipids of the rainbow trouts was examined. The astaxanthin was found to be accumulated in the rainbow trout muscle when fed for 7 days with astaxanthin supplementation(80mg/kg diet) in the form of the red yeast and the content did not increase further when fed longer up to 21 days. Seven days supplementation of astaxanthin raised the rainbow trout muscle content of the astaxanthin to 17.3$mu extrm{g}$/g tissue from 11.8$mu extrm{g}$/g tissue in mature control group. Although the hepatic TBARS level was found to be significantly decreased, the astaxanthin supplementation did not alter the $alpha$-tocopherol and TBARS contents of the rainbow trout muscle.