Abstract: An experiment was conducted to determine the effects of different doses of Liquid DL-Methionine Hydroxy Analogue (LMA) on growth performance and immune response in broiler chickens. In a single factorial arrangement with 4 levels of LMA to meet 80%， 100%， 120%， 140% of methionine requirements of broiler recommended by Feeding Standard of China (2004)， 256 one-day-old Arbor Acres male broiler chickens were randomly divided into 4 treatments with 8 replicates of 8 birds each. The growth performance， cellular and hormonal immunity were respectively determined. The results showed that， with the LMA level increased， there were no significant changes (P＞0.05) in body weight gain and feed intake among the treatments， the ratio of feed to gain was linearly decreased and it was significantly highest (P＜0.05) in the group fed with 80% of methionine requirement; the relative weight of the spleen on day 21 were higher significantly (P＜0.05) in the group fed with 120% of methionine requirement than that in the 80% group; the serum globulin on day 21 and 42 were linearly increased significantly (P＜0.05); the phagocytosis of neutral red of peripheral blood lymphocyte was quadratic and the lowest was in the control group (P＜0.05); the proliferation of peripheral blood lymphocyte in response to LPS and those of the 120% group on day 21 and of the 100% group on day 42 were significantly higher than the others (P＜0.05); the antibody titers to NDV on day 4 post first inoculation of the vaccine was quadratically increased， and the anti-BSA antibody production on day 13 post second immunization was quadratic and the hormonal immunity were highest in the groups fed with 100% or 120% of methionine requirement. In conclusion， dietary LMA supplementation improves the feed utilization and humoral and non-specific immuno-competence of broiler chickens.