To determine levels of some hematological and biochemical factors in 60 specimens (6, 12, 24 and 36 months) cultured grass carp (Rasht, Guilan Province) were sampled and blood samles were collected from caudal fin and then were analyzed. In this study, average of RBC, WBC, HCT and Hb were 1911500/mm3, 14320/ mm3, 36.3% and 7.53 gr/dl, MCV, 199.46 femtolit, MCH, 39.73 picogr., MCHC, 20.55 gr/dl. Lymphocytes, Neutrophils, Monocytes and Eosinophils were 70.91%, 26.7%, 1.06% and 1.28% and concentrations of Glucose, Cholesterol, Triglyceride and Protein were 130.6, 278.7, 243.9 mgr/dl and 3.6 gr/dl. In compared to other age groups, MCHC of 36 months old group increased, but both MCV and Triglyceride decreased (p<0.05). MCH of 6 months old group was more than other age groups (p<0.05). While in other factors such as number of WBC, differential counting of WBC, Cholesterol and Protein had not observed significant difference (p>0.05).