A randomized, double-blind human trial was conducted to assess the effect of 4- or 12-week astaxanthin supplementation (1 or 3 mg/day) on the carotenoid compositions of erythrocytes in Japanese middle-aged and senior subjects. Erythrocyte astaxanthin concentrations after 4- or 12-weeks of supplementation (3 mg/day) was significantly higher than after placebo or 1 mg astaxanthin supplementations. No differences were observed in either the carotenoid compositions or the phospholipid hydroperoxide concentrations in erythrocytes after astaxanthin intake in both the 1 and 3 mg/day groups.