Patients will in general benefit from their ordinary medication in the perioperative phase. However, exceptions and special precautions are justified with drugs that may have effects, side-effects or interactions, which are particularly beneficial or harmful during a perioperative course. This includes drugs with thrombotic or bleeding potential, antidiabetics, psychopharmaca and some of the drugs used for prophylaxis and treatment of cardiovascular disease. In such cases individual advice on dosage should be given.