This text is intended for new residents in the development of anaesthesia of the Montreal Heart Institute. It presents a classification of the risk of cardiovascular surgery used in that institution and discusses current problems encountered with this type of patient (pulmonary and coagulation problems, diabetes renal failure). The attitudes of anaesthetists of this institution towards patients' medication and premedication are also discussed. The risk is classified as usual, increased or high, depending on the presence (or absence) of several factors known to increase the risk: ventricular dysfunction, heart failure, unstable angina or recent infarction, significant involvement of other systems (unstable diabetes, renal insufficiency, significant pulmonary dysfunction), age, emergency surgery and non-cardiac surgery in the presence of important cardiac pathology. With surgical procedures carrying a high mortality, for example dissecting thoracic aneurysm, the usual risk is high and is classified as such. A table of the usual risk of current surgical procedures is proposed.