The outcomes of dietary crude protein levels (CP; 18 and 20%) and L-valine (Val.; 0, 0.1 and 0.2%) supplementation on the productive/reproductive performance, egg quality and some blood parameters of breeder Japanese quails were evaluated from 14 to 28 weeks of age. One hundred forty-four birds were individually weighed and randomly distributed into six treatment groups with eight replicates each of two females and one male. Body weight, egg weight and percentages of fertility, hatchability and total embryonic mortality were not influenced by treatments. However, significant interactions due to CP and Val. levels on egg production percentage, egg mass, chick weight and egg quality traits were obtained. Quails fed 18% CP + 0.2% Val. diets had better feed and valine intake, FCR, shell thickness and yolk index. Sexual libido, foam production, sperm concentration and motility percentage and methylene blue reaction time (MBRT) did not differ due to treatments while cloacal gland area and semen ejaculate volume of male quail were significantly improved by 18% CP level. No differences between treatments were observed for blood urea and albumin concentrations of male and female. In contrast, total protein and Superoxide dismutase (SOD) concentrations increased significantly in response to Val. levels and were also enhanced differently in the blood of male and female. Superoxide dismutase concentration in the plasma of male was not influenced by treatments while plasma female's SOD was significantly elevated due to 18 % CP + 0.2 % Val. diet. The results indicated that dietary 18% CP with 0.2% L-valine was suitable for breeder quails at 14-28 weeks of age.