Abstract—This study was conducted to determine comparative effect of supplemented Colistin and Liquid Methionine (LMA) with Capsaicin in diets on blood chemical and bacteria population in caecum of nursery pigs. Seventy-two crossbred pigs (Duroc x Large White x Landrace; initial weight 6.76±0.22 kg) were divided into three groups with six replications of eighteen piglets each. There were three dietary treatment: 1) basal diet (control) 2) basal diet with anitibiotic (Colistin 40 ppm of diet) and 3) basal diet with 0.2% LMA with Capsaicin. The results indicated that supplemental of Colistin in diets significantly decreased lymphocyte (p<0.05), increased of neutrophil and neutrophil:lymphocyte ratio (p<0.05) compared with control group. In addition, supplementing both Colistin and LMA with Capsaicin can increased population of Domain bacteria and Lactobacillus sp. in caecum of nursery pigs. In conclusion, this study indicates that supplementing of LMA with capsaicin in diets can reduce antibiotic in diets of nursery pigs.