A new agent, Molsidomine, with anti-anginal effect was investigated in 43 patients with coronary heart disease by means of 121 exercise tolerance studies. A good effect was observed 1 hour after sublingual or enteral absorption of 2 mg, which was comparable to 20 mg of Isosorbiddinitrate administered sublingually. Recorded and evaluated were the depression of ST-segment in the ECG, heart rate, systolic and diastolic blood pressure as well as subjective parameters. In comparison to the controls there was a highly significant reduction of anginal pain and ST-depression equivalent to that obtained 1 hour after Isosorbiddinitrate. The effect of Molsidomine could be established already 10 min after sublingual administration and sustained 5 to 6 hours afterwards with a highly statistic significance after sublingual as well as after enteral absorption. Side effects were noticed in 3 out of 43 patients, 2 of them with headache. The remarkable advantages of the drug are to be seen in its simple dosage and administration, its good tolerability, and its intrinsic retard-effect. A combination with beta-blocking agents seems to be possible in the same way as with Isosorbiddinitrate.