All patients should undergo surgical procedures in the most stable and favourable condition with a continuation of chronic medication. Accordingly, this medication should be continued until the day before surgery in most patients. The preoperative period should be used to evaluate the completeness and quality of the medical treatment. Are all patient with cardiological indications for beta-receptor blocking agents, ACE-inhibitors and statins treated with these drugs? Is diabetes being adequately treated? Are the doses of the medication for the treatment of thyroid dysfunction within the optimal range? If there is room for improvement, adjustments should be done cautiously and well in advance. In contrast, there are no recognised situations in which a medication should be started preoperatively in the absence of a pre-established chronic indication. Management of antiplatelet agents and cumarins requires careful consideration. The hazards of continuing and withholding treatment must be evaluated. In patients who have suffered a cardiovascular event and/or have undergone (coronary) revascularisation, elective surgery must be delayed for weeks or months depending on the circumstances and the devices used.