The author presents his own experience in bypass operations performed on 123 patients suffering from ischaemic heart disease. The paper covers the period from October 1969 to April 1974. The total mortality in this group of 123 patients was 7%. Post-operative myocardial infarction took place in 11% of the cases. The control examination made 6 months after operation showed the patency of bypass in 75% of patients. Proliferative changes were found in 10% of the cases with venous bypass. Arterialisation of the cardiac veins was performed on 21 patients because of disseminated occlusion disease of the coronary arteries. Early results are very encouraging. However, a longer observation period is needed.