Commonly used vitamins such as vitamin C is seen by many athletes as nutritional supplement rather than a performance enhancing drug that boost pulmonary function parameters. This research work is aimed at investigating the effect of vitamin C on Spirometric parameters of athletes. 100 participants were used, 50 for each test group (Vitamin C) and water as control group. Spirometry and peak flow measurements were carried out on each participant. The vitamin C administered orally at a dose of 1.50mg/kg body weight and 35ml of water given orally, the body mass index (BMI), age, sex considered. Measurements were taken before and after one hour of administration of drugs. The results show mean PEFR male and female for Ascorbic Acid test group as 535.2±207.79L/Min and 322.76±20.39L/Min respectively. Control group PEFR male and female as 364.8±23.20L/Min and 325.6±20.45L/Min respectively. Control groups PEFR male and female as 450.6±51.45L/Min and 290±34.90L/Min for Vitamin C, 318±16.26L/Min and 275.20±14.77L/Min for water respectively. Vitamin C increases PEFR much more than water, ERV, IC, VC and IVC were increased by Ascorbic Acid while water decreased ERV, IC, VC, and IVC. The vitamin C effect shows a significant (p<0.05) increase in PEFR, indicating a minimal response of smooth muscle to sympathomimetic. The research work supports the performance enhancing role of Vitamin C, more pronounced in males than females. The finding of this study actually shows that vitamin C indeed has beneficial effect on pulmonary function which means enhancement of performance of athletes. The relatively lower values in females in this study correspond with the report that progesterone reduces fatigue and lowers exercise tolerance (Van-Haren et al., 1998), the participants have high reserve expiratory abilities. This might be due to the fact that they are athletes, meaning they always engage in active regular bodily exercises.