Introduction: Clinical laboratory data are crucially important for the diagnosis, prognosis and therapy of agingrelated diseases. The age-dependent changes in the findings of routine clinical-chemistry analyses may influence the evaluation of health status of the elderly people. Serum endogenous antioxidant levels and lipid profiles are considered to be related to the progress of age-related diseases. Analyses of these routine parameters are also important for the evaluation in the elderly. Although the analyses of serum biochemical parameters are important, there have been not enough data on changes in the levels of parameters with aging in both genders. However, elderly people generally suffer from aging-related diseases or may be using some medication that interferes with the accuracy of the result; it is thus preferred that the same procedures be applied in aged rats as a model of human aging. Methods: Aged Sprague-Dawley rats (24 months) of both genders were used in the current study. Serum total protein, albumin, bilirubin, uric acid, lipid profiles, iron, and total iron-binding capacity levels were determined on the same day of collection by standard clinical chemistry laboratory methods. Results: Serum endogenous antioxidant parameters such as uric acid and bilirubin levels varied with gender in spite of almost no changes in the serum albumin and total iron binding capacity levels. Among the main parameters studied, lipid profile, conjugated bilirubin, and uric acid levels of male rats were significantly higher than in the aged female group. On the other hand, serum unconjugated bilirubin and iron levels were all found to be lower in the aged male group. Conclusion: Our findings support our conviction that serum biochemical parameters of aged rats have a controlling role in differing regulating mechanisms through gender differences. The gender-related data on these main serum clinical chemistry parameters in aged rats would be useful in studies of aging-related disorders using this model.