Because of age-related modifications of the heart, lung, and circulation, several cardiopulmonary parameters present altered normal and reference values with increasing age. Other parameters, for example, arterial blood pressure, change only insignificantly with age. In older age groups it is more difficult to establish reference ranges and values because of the lack of "healthy" subjects. To establish cardiopulmonary parameters, appropriate investigations for the age group, for example, treadmill-ergometer, should be preferred. In judging if a value resulting out of the reference range is to be considered really pathologic, other factors are to be taken into account, such as circadian variations, motivation, associated pathologies as well as the actual physical and psychological conditions, when we are dealing with older subjects or patients.