Exercise is recommended in patients with left ventricular failure. Although right ventricular failure is common in patients with a systemic right ventricle (RV), no data are available on the effect of physical activity in these patients. The aim of this study was to evaluate the relation of physical activity and cardiac function, exercise capacity, and quality of life in patients with a systemic RV. Forty-seven patients (64% men, mean age 35 years, range 21 to 69) with a systemic RV (31 with an atrially switched transposition of the great arteries and 16 with a congenitally corrected transposition of the great arteries) were included. Cardiac function was assessed by cardiovascular magnetic resonance or computed tomography, exercise tests, and serum N-terminal prohormone brain natriuretic peptide (NT-pro-BNP) levels. Habitual physical activity was assessed using the Short Questionnaire to Assess Health-Enhancing Physical Activity (SQUASH) and quality of life using the Medical Outcomes Study Short Form 36-Item Health Survey. Mean systemic right ventricular ejection fraction was impaired (36.8 +/- 7.8%), as was maximal exercise capacity (78.5 +/- 23.9% of predicted). NT-pro-BNP level was increased (median 269 ng/L, range 34 to 4,476). Mean SQUASH score was 6,808 +/- 3,241, indicating a decreased level of habitual physical activity. Although patients' scores on mental quality-of-life domains were comparable to the general population, scores on most physical quality-of-life domains were significantly lower. SQUASH scores were found to be a significant predictor for exercise capacity (p <0.01) and physical quality of life (p <0.001). However, we found no relation between SQUASH scores and right ventricular ejection fraction or NT-pro-BNP. In conclusion, physical activity in patients with a systemic RV is positively associated with exercise capacity and quality of life, irrespective of cardiac performance.