When internists are consulted to assess risks and to aid in the perioperative management of surgical patients, they often can rely on substantial clinical data to guide the consultation. Perioperative cardiac risk can be estimated based on the severity of underlying heart failure, the occurrence of a recent myocardial infarction or various arrhythmias, the presence of aortic stenosis, the patient's age, the type of planned surgery (including whether it is an emergency or elective procedure), and the patient's general medical condition. Preoperative exercise testing or cardiac catheterization to assess risk are not routinely indicated, but perioperative hemodynamic monitoring to improve management is recommended in patients at high risk. Postoperative hypertension, arrhythmias, and heart failure commonly occur in the first 2 days after surgery, but the risk of myocardial infarction persists for at least 5 or 6 days after surgery. Effective perioperative consultation must include careful postoperative observation to detect cardiac complications at an early stage and to assist in their management.