The study included 90 buffalo from Yarimjah in the southern of Mosul city, divided in to three groups, the first group (30) buffalo (1-1.5 years), second group (30) buffalo (5-8) years and the third group (30) buffalo (15-20) years to study the effect of the age progress on some physiological and biochemical parameters as indicator of oxidative stress. The results showed that all of the red blood cells, hemoglobin, packed cell volume increased significantly in the middle ages compared with other groups of the study and the lowest value in the older age group, while platelets increased gradually and significantly with age increase. In addition, white blood cells increases significantly in the middle-aged compared with the study groups, and significantly decreased in older age group while the percentage of eosinophils and neutrophils showed the highest significant value in the older age groups and the lowest value at the small ages , lymphocytes showed a gradual significant decline with increasing age compare with other study groups. monocytes appeared in the highest significant value in the middle ages and the lowest value in the older and small ages groups, there was no significant difference in basophils between the studied groups. On the other hand glutathione appeared with the highest significant value in the middle ages and the lowest value in the older ages, while malondialdehyde increased significantly with gradual age progress, this is due to an increase in free radical production and oxidative stress that accompany aging process due to antioxidants exhaustion, which is a line of defense for the body against free radicals. It was concluded from this study that with age-progress have bad effects on blood constitutes revealed by reduced in red blood cells, white blood cells counts accompanied with decrease in glutathione levels and increase malondialdehyde and which are indicators of oxidative stress and this confirms and support the hypothesis of free radicals and oxidative stress and their roles in aging.