Abstract: This study was conducted to investigate the effect of Achyranthes Bidentata Polysaccharide (ABP) on growth performance, inflammatory responses and hormones in weaned piglets after Escherichia coli Lipopolysaccharide (LPS) challenges. A total of 48 crossbred (Duroc x Large; White x Landrace) male pigs weaned at 28 days of age (8.45±0.14 kg) were randomly allotted to one of four treatments by initial BW in a 2x2 factorial design that included a dietary addition of ABP (0 or 500 mg kg-1) and immunological challenge (with LPS or saline). On day 14 and 21, pigs were injected intraperitoneally with either 100 μg kg-1 BW of LPS or an equivalent amount of sterile saline. Blood samples were obtained 3 h after injection for analysis of Tumor Necrosis Factor-α (TNF-α), Prostaglandin E2 (PGE2), cortisol, Growth Hormone (GH) and Insulin-like Growth Factor (IGF)-I. The results showed that LPS challenge decreased Average Daily Feed Intake (ADFI) (p<0.05) from 14∼21 and day 21∼28. ABP increased ADG (p<0.05) and ADFI (p<0.05) from day 21∼28. An interaction (p<0.05) between LPS challenge and diet was observed for the plasma concentration of TNF-α, PGE2, cortisol, and IGF-I after both LPS challenges such that among LPS-treated pigs, pigs fed the ABP diet were lower for TNF-α (p<0.05) and higher IGF-I (p<0.05) than those receiving the control diet. These results indicated that ABP alters the release of inflammatory cytokines that may lead to improved pig performance during an immunological stress.