Physical fitness was assessed in relation to a near maximal bicycle exercise test in two populations; population 1: 122 middle aged and elderly cross-country skiers with a documented very high physical performance, and population 2: 2014 apparently healthy men 40-59 years of age. All were without known or suspected heart disease at the baseline study. A number of so-called coronary risk factors were studied simultaneously. The total incidence of coronary heart disease (CHD) events were noted as was the total 7 year incidence of death from CHD among men from population 2. By subdividing the latter in quartiles of physical fitness within each 5 year age group--and studying levels of coronary risk factors and CHD deaths within these 16 subgroups--the following findings were made: All coronary risk factors were favourably and strongly associated with high physical fitness and vice versa in a consistent way. Death from myocardial infarction and sudden, unexpected death followed the same pattern in an inverse way. The skiers as a group closely followed the most fit men from population 2 in all respects. Thus we have noted a strong, graded, positive association between physical fitness and a number of coronary risk factors, and an inverse relationship between high physical fitness and the risk of dying from CHD. These findings hold true for a period of 7 years among middle aged men free from known or suspected heart disease.