The authors summarize results of trials with acetysalicyl acid (ASA) in patients with ischaemic heart disease and in particular with chronic cardiac failure. They draw attention to the relatively frequent use this drug in common practice, although so far not a single trial was completed which would prove the effect of acetylsalicyl acid on long-term mortality. The authors discuss also possible interactions of acetylsalicyl acid and ACE inhibitors which in retrospective analyses indicate possible veakening of the ACE-I when administered concurrently with ASA in cardiac failure. The authors mention also other antiaggregation drugs, which similarly as ASA, significantly reduce the mortality in acute coronary syndrome. Their long-term administration is however not associated with further improvement of the diagnosis. Trials are mentioned which compare antiaggregation and anticolagulation treatment in patients with ischaemic heart disease. They analyze also the effect of dosage (benefit vs. risk). After ASA > 300 mg there are more frequent complications, and without a proved effect on total mortality, while doses < or = 100 mg seem to be safer but there is evidence that they are effective in reducing the total mortality of patients with IHD and/or cardiac failure.