A 21-year-old woman suffering from increasing dyspnoea on intense physical exercise, was found to have a congenital right-sided arteriovenous pulmonary fistula. This was successfully and without complication embolized using a percutaneously introduced Gianturco wire coil. All symptoms disappeared after this procedure. Definite improvement in physical performance, in comparison with pre-embolization values, was documented by spiroergometry as early as two days later (oxygen uptake 1855 vs. 1459 ml/min; anaerobic threshold 920 vs. 790 ml/min; oxygen-pulse 10.6 vs. 8.0 ml/beat; oxygen partial pressure 77.5 vs. 67.6 mmHg; alveolar arterial oxygen difference 33 vs. 44 mm Hg). Further constant subjective and objective improvement in physical performance was demonstrated 3 months after embolization. This case confirms that embolization of a pulmonary arteriovenous fistula can rapidly achieve lasting improvement in exercise performance.