Background: Physical exercise may be associated with a 10-20 fold increase in whole body oxygen uptake. Oxygen flux in the active peripheral skeletal muscle fibers may increase by as such 100 to 200 fold during exercise. Studies during the past 2 decades suggest that during strenuous exercise, generation of reactive oxygen species (ROS) is elevated to a level that overwhelms tissue antioxidant defense systems. The result is oxidative stress. The present study aims to investigate the effect of supplementation of beta carotene, minerals and antioxidants in combination on the endogenous antioxidant system of the body (viz., glutathione peroxidase GPX, super oxide dismutase SOD and catalase CAT) of hundred females of 18-21 years age, and comparable height, and weight. Methods: Endurance capacity (min) of each subject was determined through exercise on a Magnetic Break Bicycle Ergometer at a fixed workload of 600 kgM/min till exhaustion. GPX, SOD and CAT levels were analyzed at pre and post exercise levels. The subjects (N=100) were divided into two groups – control group (n=50) receiving placebo supplementation and the experimental group (VM+Se) receiving supplementation of beta carotene and antioxidant minerals combinedly in capsular form (n=50) for 15 days. The same experimental procedure was repeated after supplementation.