Abstract: The current study was conducted to determine the effects of Salmonella Typhimurium lipopolysaccharide (LPS) challenge on egg production performance, inflammatory response, tissues metallothionein (MT) synthesis and tissue zinc distribution in laying hens fed two zinc sources. The experimental Hyline brown hens were fed with three different diets (a corn-soybean meal based diet without additional zinc supplementation and basal diet supplemented 60 mg/kg zinc from ZnSO₄ or ZnAA) respectively from 3-week old. At the age of 58-week-old, twelve hens of each dietary treatment were selected and randomly allotted in a 2×3 factorial design. On day 1, 3, 5, 7 of 58-week, six hens of each dietary treatment were injected intraperitoneally with Salmonella Typhimurium LPS or an equivalent amount of sterile saline. There was neither zinc source×immune challenge interaction nor zinc source effect on egg production, egg weight and percentage of cracked eggs during 7 d study period (P＞0.05). However, LPS-challenged birds have decreased egg production (P＜0.05) and increased percentage of cracked eggs (P＜0.01) compared to saline treated birds. When challenged with LPS, the fever response of hens fed ZnAA peaked and subsidized early relative to those fed ZnSO4 or basal diet. Among LPS-challenged birds, serum IL-1β was higher in hens fed ZnAA than those fed ZnSO₄ at 3 h post-injection (P＜0.01), however, birds fed ZnAA had the lowest serum IL-1β concentration among dietary treatments at 12 h postchallenge with LPS (P＜0.001). Among saline-treated birds, serum IL-1β was higher in hens fed ZnAA diet than those fed the basal diet at 3 h post-challenge(P＜0.01). Zinc concentration of liver and spleen tended to be higher in LPS-challenged hens fed ZnAA than those fed ZnSO4 (P＜0.09). MT concentration in liver of birds fed ZnAA diet was higher than those fed ZnSO₄ diet (P＜0.05). When challenged with LPS, birds fed ZnAA diet have a higher concentration of MT in both liver and spleen than those fed ZnSO₄ (P＜0.05). Supplementation of ZnAA increased MT concentration by 266% and 225% in liver and spleen respectively, whereas supplementation of ZnSO₄ increased MT concentration only by 158% and 151% in liver and spleen respectively. The results suggested that supplementation of zinc from ZnAA may increase tissue MT synthesis and zinc sequester in liver and spleen, then elevated the sensitivity to LPS challenge and shortened acute phase response which may be beneficial to immune defense.