Skin sensitivity to pain caused by electric stimulation was examined in 30 coronary patients with angina of effort (functional classes III-IV); pain thresholds for the right foot and right forearm were determined, as was the threshold for pain-associated flexion reflex R-III. The patients were divided into two groups on the basis of Holter's ECG monitoring: patients whose ST depressions were painless in more than half instances (Group 1), and those in whom all ischemic ST depressions were accompanied by anginal attacks (Group 2). Painless ST depressions were shown to have smaller depth and duration as compared to painful ST depressions in the same patients. Patients with predominantly painless episodes of myocardial ischemia had increased thresholds of skin sensitivity to pain and the R-III reflex.