-The objective of our study was to evaluate the effects of pineapple (Ananas comosus) leaf powder (PLP) on broiler performance. One hundred male broiler chicks (aged one day) were divided into five groups consisting of four pens as replicates, which were treated with basal diet (normal control); basal diet supplemented with 1, 2, and 3% PLP; or 50 mg/kg of zinc bacitracin (ZnB) as a positive control for 35 days. Body weights were significantly increased by 1.06, 5.67, 13.15, and 11.92%, respectively, and feed conversion ratios were decreased by 2.36, 8.49, 12.06, and 11.43%, respectively, in 1, 2, 3% PLP-and ZnB-supplemented groups, compared with the normal control group. Notably, the 2 and 3% PLP supplementations had beneficial effects on broiler performance, similar to that of the positive group. Haematological parameters, such as red blood count, haemoglobin, and haematocrit, were improved in the 3% PLP-supplemented group, but no significant differences in white blood count and its differential count were observed. The serum biochemical parameters, such as creatinine and blood urea nitrogen, were found to be decreased in the 2 and 3% PLP-supplemented groups, compared with the normal control group. Finally, 2 and 3% PLP supplementations dramatically decreased the caecal coliform and Escherichia coli populations, but increased the lactobacillus population. Taken together, our results suggest that PLP improves the performance of broilers and balances the gut microbial population. Therefore, PLP can be used as a supplement in the diet of broilers.