The authors describe the case of a 57-year-old male patient with severe left ventricular dysfunction (ejection fraction of left ventricle--37%, left ventricular end diastolic pressure 32 mm Hg) as a result of an extensive anterior Q infarction of the heart muscle. The patient did not have signs of congestive heart failure. He was treated on account of angina pectoris on exertion, grade III according to NYHA, hypertension and diabetes. Nifedipine and diltiazem administration led to repeated attacks of cardiac asthma. Calcium channel blockers should be administered to patients with angina pectoris and severe left ventricular dysfunction only when nitrates alone do not eliminate ischaemia and pain. They should be administered carefully and with the knowledge that they may in rare instances cause clinical deterioration of left ventricular function.