Changes in exercise tolerance under the impact of obsidan, corinfar, isoptin and their combinations were studied in 12 angina patients with the help of bicycle ergometry. The most marked increase in exercise tolerance following the use of a single drug was observed with obsidan (85.1 +/- 35.1%), although corinfar and isoptin also led to a significant elevation in the patients' working capacity (67.4 +/- 14.4% and 49.8 +/- 6.3%, respectively). Combination of isoptin and obsidan brought about no increase in tolerance as compared with obsidan alone whereas the combination of corinfar with obsidan showed the maximal antianginal effect.