Vigorous physical training induces left ventricular hypertrophy (LVH), a so-called "athlete's heart". The hypertrophic response represents an adaptation to the increased haemodynamic load on the heart associated with physical exercise. Wall thickness and/or left ventricular internal diameters are specifically increased depending on the type of haemodynamic load (volume- or pressure load). It is a consistent finding that left ventricular mass is increased in elite athletes when compared with sedentary controls, but few athletes have cardiac dimensions exceeding accepted normal values. Most commonly these athletes are male oarsmen. Occasionally, it may be difficult to distinguish physiological LVH from primary heart disease and therefore it is of importance also for physicians to be familiar with the "athlete's heart". Also, the sensitivity of the non-invasive methods for detecting coronary heart disease is reduced in athletes with LVH. This should be considered in the planning of the diagnostic strategy in athletes with LVH and suspected ischaemic heart disease.