The purpose of the study was to describe the clinical picture in patients with ischemic heart disease (IHD) and verifying severity of ventricular arrhythmias. The study included 856 patients with IHD aged 23-88 years (mean = 55.3), including 659 men and 197 women. Holter monitoring was performed in all patients. Ventricular arrhythmias were graded according to Lown. The patients were divided into five groups: group 1-349 patients with Lown's grade 1 and 2; group 2-95 patients with grade 3; group 3-152 patients with grade 4a and 4b; group 4-11 patients with grade 5; group 5-507 patients (selected from groups 2, 3 and 4) with Lown's grade 3 and 4 or 5. Arterial hypertension was found in 17.1%, myocardial infraction in 66%, and syncope in 12.3% of the patients. The patients with complex ventricular arrhythmias versus Lown's grade 1 and 2 show significant differences especially in respect to: the frequency of previous anterior myocardial infraction, the incidence of pain at rest, loss consciousness, the frequency of ventricular tachycardia and fibrillation, anginal pain and exercise-related arrhythmias. The patients with Lown's ventricular arrhythmia grade 3-5 do not differ significantly in their clinical manifestations of IHD from the patients with ventricular arrhythmias grade from 3 to 5. The development of silent myocardial ischemia during exercise stress testing is typical also for the patients with complex ventricular arrhythmias. A decreased contractility index, ejection fraction and dyskinesis are significantly more frequent in the patients with complex ventricular arrhythmias.