Effect of the egg yolks from laying hens intubated, p.o., astaxanthin (designated AEY) on mouse humoral immunity was investigated using male ICR mouse (6~7 weeks of age). Mice were adapted in a temperature- and humidity- controlled house for one week and randomly divided into 5 treatment groups (9 mice/cage/treatment). Mice were intubated p.o., AEY (100, 250 and 500$mu extrm{g}$) or control egg yolks (CEY, 250$mu extrm{g}$), dissolved in 0.1 mL DMSO, for consecutive 4 days. At day 5, carbon suspension (pilot drawing ink 3 mL+3% gelatine 3 mL) was injected 3 $mu$L Per 1 g body weight through tail vein. Carbon clearance time was measured at 5 and 35 minutes Post the injection of carbon suspension. Another two experiments were conducted to determine the hemagglultinin-titer (HGT) and hemolysin-titer (HLT) with male ICR mouse (8 mice/cage/treatment). Mice treated with AEY were induced immune activity with SRBC. HGT and HLT were measured from the blood at day 1 and 3 after treatment of SRBC. AEY treatment reduced the carbon clearance time. Especially the carbon clearance time by 500 $mu extrm{g}$ AEY treatment was 5.00 minutes, which was very short time compared with 9.42 minutes by control and 9.01 minutes by CEY. AEY group showed slights higher values of HGT and HLT than CEY group and control. At day 1, HGT in control, 250$mu extrm{g}$ CEY and 250$mu extrm{g}$ AEY groups was 5.50, 5.63, and 6.00, respectively. Similiarly, HLT in control, 250$mu extrm{g}$ CEY and 250$mu extrm{g}$ AEY groups was 4.75, 5.38, and 5.50, respectively, at day 1. These results suggest that AEY exhibited immunity-enhancing effect.