Over the last two decades, it has become increasingly clear that reactive oxygen species (ROS), including free radicals are involved in cardiovascular diseases. In recent years, there has been a growing interest in the clinical implications of these oxidants. The ROS are common by-products of many oxidative biochemical and physiological processes. Therefore the present study was carried out to evaluate the total antioxidant capacity, lipid peroxidation and status of superoxide dismutase in patients with cardiovascular diseases. Total 185 patients of both sexes were included in the study and further classified into 3 groups as hypertensive, Ischemic heart disease and cerebrovascular disease/stroke. The 60 healthy subjects who were not on any kind of prescribed medication or dietary restrictions were included in the control group. MDA is estimated as a marker of lipid peroxidation, levels were significantly increased in all groups than controls (p<0.001). Superoxide dismutase and glutathione reductase activities was significantly low er in all groups than control (p<0.001), GPX levels were decreased in all groups except hypertension (p<0.001), NO level were decreased in all the groups except cerebrovascular disease / stroke when compared to the control. Significantly lower level of total antioxidant capacity and prominent scavenger of superoxide anion radicals suggests that failure of antioxidant defense mechanism against oxidative stress may be an important factor in the pathogenesis of cardiovascular diseases.