This study aimed to describe and reveal the health promoting activities associated with polyphenol in grape seeds (GS) supplemented to grower diets of Japanese quail. A total of 270, one day-old quail were distributed at equal body weights into three groups: 1- as a control group (with no additives), 2- control diet +1% GS (powder), and 3- control diet+3% GS to examine the effect of GS supplementation on the growth performance, carcass characteristics, serum biochemical indices, antioxidants status, immune response and intestinal microflora in Japanese quail. The most important results revealed that, inclusion of GS in quail diets improved growth performance tested at 38 days and during the period from 10 to 38 days of age, desirably decreased total cholesterol lipid profile, random blood sugar and liver enzyme activities, increased glutathione peroxidase, immune responses (IgG, IgA and IgM) and decreased thiobarbituric acid- reactive substances as compared with the control group, increased Lactobacillus spp as compared with the control group and decreased thenumber of both E-coli and Salmonella as compared with the control. Therefore, GS up to 3% can be used as a growth promoter without impairing quail growth.