This study aimed to examine effects of acute and chronic submaximal exercise on plasma renin and aldosterone levels in football players. Seven apparently healthy, male footballer subjects took part in the study. The subjects were exercised on ergometric bicycles for 20-min at 75% of Max VO 2, 3 days a week for 4 weeks. Blood samples were collected on 4 occasions: before the exercise, immediately after the exercise, as well as 2 hours and 24 hours after the exercise. Plasma renin and aldosterone levels (RIA) were measured. Exercise significantly increased plasma renin and aldosterone levels of the athletes before and after the exercise (p < 0.05). The levels at the 2nd hour following exercise dropped significantly in comparison to those immediately after the exercise (p< 0.05). Plasma values one day after the exercise were significantly lower than those after the 2nd hour (p < 0.05). Consequently, acute and 4-week chronic submaximal exercise have significant effects on plasma renin and aldosterone levels in football players (p< 0.05). © 2011 - IOS Press and the authors. All rights reserved.