Abstract: The occurrence,migration,tissue localization and quantity changes of CD3＋,CD4＋ and CD8＋ T lymphocytes in chicken rectum were examined with the CD3,CD4,and CD8 monoclonal antibodies by immunohistochemical method.The results showed that T lymphocytes cells first appeared at 7-day-old.The quantity of T lymphocytes didn’t increase obviously at 1-4 day-old hatched,CD4＋ T lymphocytes mainly distributed in lamina propria of subcut aneous in intestinal villus,small quantity distributes in muscularis mucosae and lami-na propria mucosae at 7-day-old,CD3＋ T lymphocytes distributed in muscularis mucosae and lamina propria mucosae,small quantity of CD8＋ T lymphocytes distributed in muscularis mucosae.T lymphocytes kept increasing with the increase of age,large quantity distributes in mucous layer,and reached stable at 21-day-old.Among the three types,the number of CD4＋ cells was the most and CD8＋ were the least all the time.The results confirmed that the humoral immune function of rectum in chicken strengthened quickly after hatching,and reached the mature level at 21-day-old.