The present study was designed to investigate the efficacy of overdose of vitamin C supplementation on growth performance, Europe production efficiency factor (EPEF),carcass traits and some blood constituents of Japanese quail in one way analysis of variance experiment lasted 49 days of age. Two hundred and twenty five of one day old Japanese quail chicks were used.  The chicks were distributed into 5 treatments of 3 replicates of 15 birds each. Five levels of vitamin C (0, 65, 130, 260 and 520mg/kg diet) were used. The body weight and feed intake were recorded weekly and consequently, body weight gain and feed conversion ratio were calculated. At the end of the experiment, three birds from each group were slaughtered to evaluate carcass parts. Blood serum samples were obtained from chicks at 49 day of age after being centrifuged to measure total protein, cholesterol, glucose, calcium, phosphorus and GPT. The results at 49 days of age, showed that the Japanese quail chicks fed  130 mg of vitamin C/kg were significantly (P<0.05) the best and recorded better values for body weight, body weight gain and feed conversion ratio compared to control and the other treatments.. No significant (P>0.05) effects due to vitamin C supplementation were noticed on dressed%, EPEF, and some blood serum parameters measured, although, there where slight improvements in chicks fed 130 mg/kg feed. It was recommended that feed formulation   during starter and grower periods, it should be supplemented at least by 130 mg/kg of vitamin C to achieve good performance and health of Japanese quail.