In a double-blind study 40 patients with coronary heart disease, who all complained of typical exertion-dependent angina pectoris symptoms and showed ECG changes after work in conformity with a myocardiac hypoxia, were examined in ergometric exertion tests before as well as immediately and 60 minutes after a single dose of 3.75 mg of Isoket-spray or Placebo-spray respectively. The Isoket-spray group was compared with the placebo group, furthermore, within the Isoket-spray group, the original ergometry (without medication) and the subsequent ergometries. The ST-depression, the time until reattainment of the original electrocardiographical situation after cessation of exertion and the subjective complaints showed highly significant improvements after use of the Isoket-spray in both repeated ergometries. Rapid and long-term relief after application of Isoket-spray were thus impressively shown in this double-blind study.