There has been increasing emphasis on maintaining the patients' quality of life while on antihypertensive therapy (e. g., regular physical activity as a lifestyle modification) . However, no information is available on the effects of regular swimming exercise on mental health despite the popularity and potential benefits of this life-style modification. To determine the efficacy of swim training on mood states, 19 obese subjects with stages 1 to 2 essential hypertension were randomly assigned to either a swim training (n=12) or control group (n=7) . Subjects were assessed before and after a 10 week supervised swim exercise program with the Profile of Mood State (POMS) questionnaire. The swim training group completed an average of 94% of the scheduled exercise sessions, and were able to gradually and significantly (p<0.05) increase daily swim distance. Additionally, resting heart rate was significantly reduced (p<0.05) . Swim training resulted in significantly higher (p<0.05) vigor-activity scores. In addition, anger and fatigue scores were 34 and 28% lower after the swim training period. No significant changes were observed in any of the POMS scores in the control group. The improved mood state observed after swim training may have a clinically important influence on the quality of life in these subjects with essential hypertension.