The study was to observe the effects of different levels of rumen-protected leucine (Leu) and β-hydroxy β-methylbutyrate-Ca (HMB-Ca) on immune function of Inner Mongolian White Cashmere goats （IMWCG）. Twenty-one wethers of IMWCG in half-sib were randomly divided into 7 groups according to body weight. Goats in control group were fed basal diet, goats in the six experimental groups were fed diets supplemented with different levels of Leu and HMB-Ca ［0.5 g/d HMB group (group A), 1.0 g/d HMB group (group B), 1.5 g/d HMB group (group C), 0.5 g/d Leu group (group D), 1.0 g/d Leu group (group E) and 1.5 g/d Leu group (group F)］. The results suggested that different levels of rumen-protected Leu and HMB-Ca could increase lysozyme （P＜0.05）, IgG and IgM contents in serum, but decrease the levels of serum soluble CD4 and CD8, and group C got the best effects (P＜0.05). The experiment indicates that rumen-protected Leu and HMB-Ca play important roles in enhancing the body immune function.［Chinese Journal of Animal Nutrition, 2010，22（6）:1762-1767］