The aim of this study was to investigate the effects of different levels of maca powder supplementation (0.0, 0.5, 1.0, 1.5, 2.0, and 2.5 g/kg) in the diet on performance, carcass characteristics, serum biochemical constituents and hormone concentrations, bone biomechanical properties, and ileum histomorphology in growing Japanese quails. In this 42-day trial, a total of 480 mixed sex Japanese quail chicks, aged 1 day, were randomly distributed among six experimental groups. Each experimental group contained four replicates of 20 chicks each. The addition of 2.0 g/kg of maca powder to the diet significantly decreased body weight, body weight gain compared to the control group (P < 0.05). In addition, with the 1.5 g/kg level of maca powder, feed efficiency improved considerably (P < 0.05). The testis weight increased significantly with the addition of maca powder at 1.0 g/kg level to the diet, and testesteron concentration of serum in male quails was also increased significantly at 1.5 g/kg level of maca powder compared to control group (P < 0.05). The addition of 2.5 g/kg level of maca powder significantly reduced the cholesterol concentration of serum in male quails compared to the control group (P < 0.05). The administration of 2.0 g/kg level of maca powder to the diet caused a decrease in shear force (P < 0.05). The addition of maca powder to the diet significantly increased crypt depth and villus surface area at 0.5 g/kg level, villus width at 1.0 g/kg level, and villus height at 2.0 g/kg level in growing quails (P < 0.05). According to the results obtained from the present research, it can be said that the addition up to 2.0 g/kg maca powder to growing quail diets could improve feed efficiency, testesteron concentration of serum, and ileum properties.