This study evaluated whether arginine (Arg) supplementation could attenuate gut injury induced by Escherichia coli lipopolysaccharide (LPS) challenge through an anti-inflammatory role in weaned pigs. Pigs were allotted to four treatments including: (1) non-challenged control; (2) LPS-challenged control; (3) LPS+0·5 % Arg; (4) LPS+1·0 % Arg. On day 16, pigs were injected with LPS or sterile saline. At 6 h post-injection, pigs were killed for evaluation of small intestinal morphology and intestinal gene expression. Within 48 h of challenge, 0·5 % Arg alleviated the weight loss induced by LPS challenge (P = 0·025). In all three intestinal segments, 0·5 or 1·0 % Arg mitigated intestinal morphology impairment (e.g. lower villus height and higher crypt depth) induced by LPS challenge (P < 0·05), and alleviated the decrease of crypt cell proliferation and the increase of villus cell apoptosis after LPS challenge (P < 0·01). The 0·5 % Arg prevented the elevation of jejunal IL-6 mRNA abundance (P = 0·082), and jejunal (P = 0·030) and ileal (P = 0·039) TNF-α mRNA abundance induced by LPS challenge. The 1·0 % Arg alleviated the elevation of jejunal IL-6 mRNA abundance (P = 0·053) and jejunal TNF-α mRNA abundance (P = 0·003) induced by LPS challenge. The 0·5 % Arg increased PPARγ mRNA abundance in all three intestinal segments (P < 0·10), and 1·0 % Arg increased duodenal PPARγ mRNA abundance (P = 0·094). These results indicate that Arg supplementation has beneficial effects in alleviating gut mucosal injury induced by LPS challenge. Additionally, it is possible that the protective effects of Arg on the intestine are associated with decreasing the expression of intestinal pro-inflammatory cytokines through activating PPARγ expression.