In birds, exogenous melatonin possesses a wide spectrum of biological effects and can interfere with a wide range of behavioral and physiological processes including growth but the underlying mechanisms under feed restriction conditions have not been well defined. This study was carried out to investigate the effects of melatonin on growth performance, gut health, and some biochemical parameters of broilers subjected to feed restriction. Eleven-day-old male Ross 308 broilers were randomly distributed to 3 dietary treatments with 6 replicates of sixteen chicks each as follows: (1) control (CON); (2) 20% feed restriction (d 11–18; FR); and (3) the same as FR group, but melatonin was supplemented to drinking water (30 µg/ml, d 11–35; MFR). All birds had access to feed and water from 18 to 35 d of age. At d 35, broilers were sampled for quantification of blood components, intestinal morphology, and microbial counts. Supplementation of melatonin improved feed conversion rate of feed restricted birds (P