We have studied the relationship between the onset of an anginal attack and ST depression exceeding 1 mm and the quantity of silent myocardial ischemia episodes on Holter monitoring in 59 patients with stable class II-III angina. No patient with early angina attacks demonstrated silent ischemia predominance. Every third patient with simultaneous pain and ST depression demonstrated silent ischemia over 75%. If an angina attack appeared 60 sec after an ST depression, almost half of such patients had silent ischemia over 75%. The time ratio between angina onset and ST depression is a value revealing patients prone to the silent course of the disease