To explore the effects of γ-amino butyric acid (GABA) on growth performance and hormone levels in serum of weanling piglets, 45 crossbred piglets weaned at age of (28±2) d were randomly allotted to be fed one of three diets containing 0, 0.04％ or 0.08％ GABA for 28 days. There were five replicates per treatment with three piglets in each replicate. Results showed that GABA increased average daily gain (P=0.0489) and average daily feed intake (P=0.0356) from 43 to 56 days of age (P<0.05). No significant effect of GABA was observed on the ratio of feed to gain (P>0.05). There was an increasing tendency of feed intake (P=0.1107) and average daily gain (P=0.1317) with supplementary levels of GABA during the whole trial period. The supplementation of 0.08％ GABA increased the levels of gastrin and insulin in serum of piglets at 42 and 56 days of age (P<0.05). And 0.04％ GABA increased the level of gastrin in serum of piglets at 56 days of age (P<0.05). Free fatty acid (FFA) in serum of piglets fed GABA increased significantly (P<0.05) at 42 days of age, and 0.08% GABA increased the level of FFA in serum of piglets at 56 days of age (P<0.05). Moreover the two GABA groups had a higher lipase activity in serum of piglets at 42 and 56 days of age, and the lipase activity in serum of piglets in 0.08% GABA group increased compared with 0.04% GABA group. The results indicated that GABA improved feed intake and average daily gain in a shortterm mode, which was involved in changed gastrin production modulated by GABA.