Both ventilation and perfusion scintigraphy are accurate predictors of post-operative ventilatory function. Previous attempts to predict post-operative exercise capacity after lung resection using radioisotope scintigraphy are few and results are conflicting. We studied 32 patients before and 6 months after pulmonary resection for bronchogenic carcinoma to assess the value of lung perfusion scintigraphy for the prediction of post-operative forced lung volumes and parameters on maximum exercise, including maximum ventilation and maximum oxygen uptake. Nine patients were lost to follow-up, and these patients differed from the reinvestigated patients only in the staging of the pulmonary carcinoma and not in preoperative lung function or exercise capacity. We found a clear relationship between the values predicted from a preoperative perfusion scintigraphy, spirometry and a maximum exercise study and the observed values measured 6 months post-operatively. The method underestimated the post-operative values of both spirometric and exercise measurements, especially in the higher range. Only in a few cases were the post-operative observed values less than the predicted values, and in these cases the difference was without clinical significance. Unexpected post-operative respiratory insufficiency was not observed. In conclusion, in patients in whom a pulmonary resection was performed, not only the post-operative spirometric values, but also the more functional related maximum exercise data can be predicted through the knowledge of a preoperative perfusion scintigraphy.