Even though lutein can stimulate immunity and decrease cancer growth, no systematic studies are available on the uptake of lutein in mice. We studied the uptake of lutein in 8-wk-old female BALB/c mice fed a diet containing 0, 0.05, 0.1, 0.2 or 0.4% lutein. Mice were killed on d 0, 3, 7, 14, 21 and 28 (n = 6/period), and blood, spleen and liver were collected. Food intake and body, liver and spleen weights did not differ among treatment groups. Lutein + zeaxanthin were not detectable in the plasma, liver and spleen of unsupplemented mice. Mice fed lutein showed very rapid lutein + zeaxanthin absorption. On d 3, concentrations of plasma lutein + zeaxanthin had rapidly increased (P < 0.05) in lutein-fed mice and no further increases were observed. Plasma lutein + zeaxanthin concentrations did not differ among lutein-fed mice by d 7 (2.58 +/- 0.2 micromol/L). Even though maximal uptake of plasma lutein + zeaxanthin was observed by d 3, uptake of lutein + zeaxanthin by the liver and especially by the spleen generally continued to increase (P < 0.05) through d 28 to reach concentrations of 0.11 +/- 0.001 (spleen) and 0.71 +/- 0. 0002 (liver) nmol/g. Therefore, dietary lutein is readily absorbed into the plasma and taken up by liver and spleen of mice. Plasma lutein + zeaxanthin concentrations were higher than in human studies; however, mice were fed lutein at a level several hundredfold greater than in humans. The liver is a major storage organ for lutein + zeaxanthin in mice. Uptake of lutein + zeaxanthin by the spleen suggests a role for lutein in modulating immunity.