Objective: To study the changes of serum interleukin levels and immune function of rats under stress. Method: 18 male rats were randomly divided into two groups, stress group (10) received "psychosocial"stress and their serum were taken after 1 hour; control group (8). Serum interleukin 2, 6, 8 and cortisol levels of all subjects were determined. Results: Compared with control group, the level of serum cortisol increased after stress (6.51?2.5/3.76?0.4 (ug/dl, t=3.45, P