The experiment was conducted to determine the effects of different immune stress on growth performance, nutrient digestibility, serum biochemical parameters and meat quality of broilers. Five hundred and forty Cobb500 broilers aged 1 day were randomly assigned to 5 groups ［group 1: control group without experimental stress, group 2: stress from simplified vaccination, group 3: stress from general vaccination, group 4: stress from lipopolysaccharide (LPS) injection and general vaccination, group 5: stress from cyclophosphamide (CPM) injection and general vaccination］ with 9 replicates per group and 12 birds per replicate. Broilers were killed and samples were collected to measure some parameters on d 21 and 42. The results showed as follows: ratio of feed to gain and apparent digestibility of energy had no significant difference among 5 groups (P>0.05). There were no significant differences in feed intake and body weight gain between groups 1 and 2 and group 3 (P>0.05). Body weight gain of broilers in the whole period (d 1 to 42) was significantly decreased by LPS stress (group 4) and CPM stress (group 5) (P<0.01), and feed intake was significantly decreased by LPS stress (P<0.05). Different immune stress significantly decreased the apparent digestibility of dry matter (P<0.01) and crude fat (P<0.05) in broilers on d 22 to 42, except that the apparent digestibility of dry matter in group 3 had no significant difference with that in group 1 (P>0.05). Crude protein apparent digestibility in ileal of broilers on d 22 to 42 was significantly decreased by CPM stess (P<0.05), and the drip loss was significantly increased by CPM stess (P<0.01). In conclusion, there are no adverse effects on growth performance of broilers without vaccination in the condition of rational feeding environment. However, immune stress decreases the apparent digestibility of dry matter, crude fat, ileal crude protein, feed intake and body weight gain, and it is adverse to the performance of broilers.［Chinese Journal of Animal Nutrition, 2010，22（6）:1551-1557］