The level of total carotenoids in the liver of ApoA-I−/−/Bco2−/− mice was increased but reduced in serum, RPE/choroids, and retina relative to the Bco2−/− mice, suggesting HDL participates in the carotenoid transport from the liver to the eye. Twenty ApoA-I−/−/Bco2−/− mice and twenty Bco2−/− mice were used in the feeding experiments. Total carotenoids consist of lutein, zeaxanthin, and β-carotene. The carotenoids of the liver and serum were extracted from individual animals, while the ocular tissues of five animals were pooled together for carotenoid extraction. *, P<0.05. Error bars represent standard deviation.