Chromium has been recognized for decades as a nutritional factor that promotes the growth of broiler chickens, but the molecular mechanism is still not clearly understood. The present study was designed to investigate the physiological and molecular mechanisms of the effects of supplemental chromium picolinate on the growth of broiler chickens. A total of 144 21-day-old Arbor Acres male broiler chicks were randomly divided into a control and an experimental group. The control group was fed a basal diet, and the experimental group was fed the same basal diet supplemented with 200 μg/kg chromium picolinate. The experiment lasted for three weeks from day 28 to 42of the birds.. Supplementation with 200 μg/kg chromium picolinate significantly increased body weight (P ＜ 0.05). Serum insulin levels in chickens of the experimental group were increased significantly (P ＜0.05 ), whereas serum glucose concentrations were decreased ( P ＜ 0.05). No significant changes were observed in serum lipid profiles in chickens fed the diet supplemented with chromium picolinate. Gene expression levels of the insulin receptor (IR) and insulin receptor substrate 1 (IRS-1), two pivotal components of the insulin signaling pathway, were also investigated using Real-time quantitative PCR. IR expression was significantly (P ＜ 0.05) increased following chromium supplementation. Therefore, supplemental chromium picolinate had a beneficial effect on the growth of broilers. In agreement with observations in mammals, chromium might exert its effect via potentiating insulin action, and ultimately by stimulating anabolism without altering body composition in chickens.