Variations in serum biochemical profile with increase in age were analyzed in turkeys (Meleagris gallopavo). Genderwise variations and effect of rearing systems i.e. free range, semi-intensive and confinements were also assessed from 1st to 6th month of age. Total sixty (n = 60) experimental birds were divided in to three groups i.e., poults having age 4-8 weeks (10 ♂ and 10 ♀), growers with age 14-20 weeks (10 ♂ and 10 ♀) and adult birds with age 24-30 weeks (10 ♂ and 10 ♀).Variations were recorded in serum biochemical profile with increase in age. Significantly, (P<0.05) higher values of cholesterol 8.39±0.48 mmol/L, globulin 2.71±0.34 g/dL, albumin g/dL 3.82±0.58 g/dL, total protein 5.35±0.55 g/L, urea 26.95±0.65 mg/dL, creatinine 0.83±0.01 µmol/L, alanine aminotransferase (ALT) 35.56±1.16iu/L and aspartate aminotransferase (AST) 44.16±1.83 iu/L were recorded for adult birds while alkaline phosphatase (ALP) values were significantly (P<0.05) higher 104.86±16.39 iu/L in grower birds. Similarly, the rearing systems also influenced biochemical parameters of M. gallopavo and significantly (P<0.05) higher values for cholesterol 6.18±0.07mmol/L and ALT 31.26±1.67 iu/L were recorded in birds reared under confinement rearing system. Values for globulin 1.92±0.36g/dL and creatinin 0.77±0.08 µmol/L were higher in birds reared under semiintensive rearing system while significantly higher urea concentrations 33.45±3.39 mg/dL were recorded from the serum of the birds reared under free range rearing system. However, non-significant variations in albumin, total protein, ALP and AST were recorded for all the three rearing systems. Significantly higher values of cholesterol, globulin, albumin, creatinine and ALT were recorded from serum of male M. gallopavo while urea and ALP were higher in hens’ serum. However, non-significant variations were recorded for total protein and AST among both the genders. It can be concluded from the present study that age, gender and rearing systems strongly influence blood biochemical profile in M. gallopavo.