The chick performance, carcass traits and some blood biochemical parameters of Japanese quails fed high energy diet containing different protein levels were studied for 42 days. Sixty quail chicks at hatch (average weight 7.02 g ± 0.12) were randomly distributed into five experimental groups (12 chicks/each). Quails in the five groups were fed ad libitum on the respective isocaloric experimental diets (3200kcal ME/kg diet) containing five dietary protein levels (18, 20, 22, 24, 26 %). The growth performance, carcass characteristics and some blood biochemical parameters were assessed. The results showed that, quails fed on high energy diets containing 22, 24 % protein in the third and fourth groups achieved significantly (P<0.05) better results, and recorded highest gains (188.0 & 189.4 g, respectively) with lowest feed intake. Highest weight gain averages with greatest values of feed conversion (2.84 & 2.71) were recorded in the third and fourth groups of quails, respectively. Dressed carcass as a percentage of live body weight was maximum in quails offered high protein diets in the fourth and fifth groups (73.21 & 73.06%), while the lowest were recorded in the first three groups fed low protein diets (68.12, 68.45 & 68.19 %, respectively). Dietary protein levels had no significant (P<0.05) effect on the internal organ weights. Uric acid, calcium and inorganic phosphorous were increased significantly (P<0.05) with increasing dietary protein levels, while had no significant effect on serum triglycerides, cholesterol and glucose. It could be concluded that, quails fed on diet having 3200kcal ME/kg with 22 % crude protein, supplemented with limiting amino acids, recorded the best results in weight gain and feed conversion, in addition to economical feed efficiency.