To investigate the effects of dietary supplementation with hydrolyzed wheat gluten (HWG) on growth performance, cell immunity and serum biochemical indices of weaned piglets, 160 crossed (Large White x Landrace) and weaned piglets were randomly divided into 4 treatments with 4 replicates of 10 piglets each. The piglets in each treatment were fed an experimental diet containing either 0 g kg^-1 HWG (control group), 30 g kg^-1 HWG (3% HWG group), 50 g kg^-1 HWG (5% HWG group), or 2.5 g kg^-1 glycyl-L-glutamine (0.25% Gly-Gln group). The results showed that the diarrhea rates in 3% HWG and 5% HWG groups were significantly lower than in control group from d 1 to 14 (P<0.05). When compared with control group, dietary supplementation with 3% HWG increased the ratio of CD₄ ⁺:CD₈ ⁺ and the ratio of serum albumin and globulin concentrations (A:G) on d 14 and 28, as well as the proliferation of T- and B-lymphocytes (P>0.05) on d 28. In addition, on d 14 and 28, the A:G ratio in 5% HWG group was significantly higher than in control group (P0.05). Interestingly, 0.25% Gly-Gln group had higher proportion of CD₃ ⁺ (P>0.05) and CD₄ ⁺ (P<0.05) on d 14 than control group, but growth performances of 0.25% Gly-Gln group were negatively affected at all experiment stages. These results suggested that HWG might improve the growth performance of piglets by strengthening cell immunity and decreasing the occurrence of diarrhea during the prophase after weaning.