An experiment was conducted with Wild Japanese quail (Coturnix coturnix japonica) to find out the best dose of the supplementation of dietary selenium (Se) and evaluate its effects on reproductive performance and egg quality traits. Initially, a 2-week trial of dietary Se supplementation with 0, 0.02, 0.2, 2 and 20 mg/kg feed was performed on 48 quail (36 laying females and 12 adult males). There were 3 males and 6 females under a dietary treatment group those had been housed in a pen of 1 male 2 females as a replication. Under standard management and feeding regime, 2mg/kg feed supplementation of Se was found to be the best dose of highest combined performance index (CPI). Upon selecting the best dose, the supplementation was continued to the similar birds for further 5-week period. During the extended period, an increased rate of egg production along with higher egg weight and shell weight was observed in the Se supplemented group compared to the control. A decrease in fertility rate and some other egg quality parameters were noticed at the terminal week of supplementation. However, Se supplementation during further 5-week period had no effect on yolk weight. Current findings suggested that none of the doses of the Se supplementation to laying quail for short-period excel a single trait but achieve the higher CPI, but longer period supplementation can negatively impact the reproductive trait. Therefore, the duration of a single dose of Se supplementation in laying Japanese quail needs consideration on purposes.