A thirteen week feeding trial was conducted to determine the effects of feeding varying levels of dietary protein on productive performance, egg quality traits, erythrocyte osmotic fragility and haematological parameters using 195 six weeks old laying quails. The birds were randomly allocated to five dietary treatment groups of thirty nine (39) birds each, and were further replicated three times with thirteen (13) birds per replicate. They were fed five experimental diets containing 17, 18, 19, 20 or 21%CP. Feed and water were provided ad libitum through out the experimental period. The results obtained showed significant (p<0.01) enhancement on percent hen-day egg production (HDEP), hen-housed egg production (HHEP), average daily feed intake, average daily protein intake and feed conversion ratio as the dietary protein level increased. Egg traits like egg size, yolk weight, yolk diameter, yolk index, albumen height, egg shell weight and shell thickness improved significantly (p<0.01) at higher protein levels (20 and 21%CP). However, egg width, yolk width, albumen weight and egg shape index were not significantly (p>0.05) affected by dietary protein levels. The cost of producing 1g of egg in the treatment groups were N0.32, N0.31, N0.29, N0.27 and N0.27 for 17, 18, 19, 20 and 21% dietary protein levels respectively. The haematological results indicated that the lowest haemolysis of 37.37 ± 6.81 % was recorded at 0.85 % NaCl concentration in quail placed on 21 % CP and this increases as the crude protein level decreases while the haematological parameters showed that the highest values was obtained for packed cell volume, haemaoglobin concentration, total erythrocyte count and total protein in the quail placed on 21 % CP while the lowest value (p < 0.05) was recorded in the group of quail placed on 17 % CP. It was thus, concluded from the results of this study that 21% CP is required in the diets of laying Japanese quails under a hot-humid tropical environment and also it was demonstrated for the first time, that high CP level up to 21 % maintain the erythrocyte membrane integrity thereby preventing oxidative stress and haemolysis and thus improves haematological parameters in quail tremendously and the study also shows direct correlation between protein intake and serum protein level.