A total of 82 patients with functional class II angina pectoris who had sustained myocardial infarction and took obsidan, 80-120 mg/day, were studied. Twenty-eight per cent had deteriorated microcirculation by 15% as compared to the baseline levels. Narrowed arterioles, diminished volumetric blood flow in forearm muscles, decreased skin oxygen supply were found at days 3-5. There was higher erythrocyte aggregation, lower deformability, and decreased skin oxygen uptake at days 10-12. A combination of obsidan and trental, 300-400 mg/day, eliminated adverse effects in the microcirculatory bed in the absence of an excessive drop in blood pressure.