This study aimed to investigate the effect of highly protein diet on some haematological and serum biochemical parameters in female and male Japanese quail (Coturnix japonica) at different age stages. Three different age stages of birds (0-30, 30-44 and >44 days) were included. After measuring the weight of birds, they were slaughtered and a blood samples were taken. Based on the results, there was an increase in the general protein and albumin in females and males at the age 3 months. The globin was higher in males. Reagrding the ratio of phosphorus and calcium, they were higher in females than males and alkaline phosphate and hemoglobin were elevated in males at 3 months of age, and in females was raised at 1st month. An increase from the normal level of total protein, albumin, calcium, hemoglobin and, alkaline phosphatase and a decrease of phosphorous and globin were observed by ageing. Many of the parameters were different significantly between sexes. © 2021 Iranian Society of Ichthyology.