Left ventricular function was investigated at rest and during submaximal exercise in 191 healthy subjects, including 46 women, by means of radionuclide ventriculography (RNV). As global parameters of heart function, ejection fraction (EF) and maximal rates of volume change during systole (VS) and diastole (VD) as well as endsystolic volume (ESV) were determined. These parameters were calculated for four age groups with mean ages of 32, 45, 55, and 64 years, respectively. At rest, heart rate (HR), EF, VS, and ESV were not significantly different in all age groups, whereas VD decreased with increasing age from 3.3 +/- 0.6 s-1 to 2.6 +/- 0.6 s-1. During exercise, HR, EF, VS, and VD increased in all groups, but less in the elderly. The smaller increase of EF and VD could be accounted for by HR alone. VS was both HR- and age-dependent. The age dependence of VD (at rest) and VS (under exercise) may reflect a reduction of myocardial compliance with increasing age. Differences of EF and VS with respect to sex were not observed, whereas VD was slightly lower in males.