In the course of a prospective study on coronary heart disease (CHD) risk factors, systolic time intervals (STI) were measured at rest in 92 men aged 52--56 yr and free of any clinical symptoms of CHD. The ratio preejection period/left ventricular ejection period (PEP/LVEP) was significantly augmented in current smokers vs nonsmokers (0.406 +/- 0.075 vs 0.384 +/- 0.068, P less than 0.05). The regression of this parameter on cigarette consumption per day, taking into account heart rate, systolic blood pressure, body mass index, serum cholesterol and triglycerides, remains significant. An acute experiment, involving 50 smokers recruited similarly, showed no significant variation of the STI after the smoking of 2 cigarettes. We concluded that the augmentation of the PEP/LVEP ratio may represent a chronic effect of tobacco smoking on cardiac function.