Changes in the make-up of our population and society in general mean that more older people are driving and continuing to drive, and older people are driving many more miles than ever before; it can rarely be assumed that any adult patient does not drive. However, older people are more likely to be suffering from serious illnesses, often from several different disease processes, and are more likely to be taking prescribed medication that may influence their ability to drive safely. This is in addition to any age-related cognitive and physical limitations they may be experiencing. Older people are also much more vulnerable to injury and death in an accident because of their increased physical frailty. In addition to the added complication of normal age-related changes which may affect driving skill, and the increased incidence of disease, older patients are a particular concern with respect to the effects of medication because of changes in metabolism and reductions in spare capacity in both physiological terms such as homeostatic mechanisms or efficiency of drug excretion, and in cognitive terms such as reduced information processing capacity, reduced peripheral attention and speed of reaction. It is suggested that a model of 'severity of all combined effects' is the most appropriate one to take when giving advice to older patients, taking into account any obvious evidence of normal age-related changes, such as changes in eyesight, speed and strength of movement, slowing of reaction times, in combination with the possible effects of disease and the medication prescribed. This document presents all of these these points in greater detail, giving a summary of studies involving illnesses commonly associated with age and of commonly prescribed medication of particular concern in relation to driving performance and risk.