Adverse drug events are common, especially in risk groups such as elderly persons. Many of the adverse drug events are preventable. The age-related changes in the different body functions have an impact on drug therapy: adjustments are required for the selection of drugs and dosages in elderly patients. Kidney function declines with age; as a consequence, drug excretion via the kidneys declines with increasing age. Also, the metabolic clearance of drugs that display a high hepatic extraction is reduced in elderly persons and the dosage of these drugs should be adapted. The present review summarizes the main findings related to the topic. Human beings make errors. Ensuring patient safety is a key issue. For elderly patients more information is required to establish a solid knowledge base. It is therefore necessary to include elderly patients in appropriate clinical trials in order to ensure that the necessary information can be accumulated.