In 24 patients (pts) with proven coronary artery disease, stable angina pectoris (AP) and elevated pulmonary artery pressure (PAP) during bicycle exercise, the acute and chronic (4 and 8 months) effects of several long-acting nitrates in different dosages: 50-300 mg pentaerythrityltetranitrate (PETN) or 40-120 mg isosorbide dinitrate (ISDN) were evaluated in comparison to sublingual nitroglycerin. Nitroglycerin was about 30%-40% more effective than PETN and ISDN with regard to pulmonary artery pressure at exercise. Beneficial effects of both long-acting nitrates were shown with regard to the number of anginal attacks, nitroglycerin consumption, and ST-segment depression both during short- and long-term treatment. Both nitrates decreased exercise pulmonary artery pressure by 15%-20%, at acute testing and during chronic therapy. There was no difference with respect to the long-term effects of both long-acting nitrates. However, more side-effects were observed during ISDN treatment. There were no signs of nitrate tolerance development with the therapy schedules under investigation.