To determine the long-term effects fo cigarette smoking on cardiorespiratory function under stress. The chronic effects of cigarette smoking on ventilatory and cardiovascular response to exercise were studied in fourth healthy male university students. The subjects were separated into two groups, smokers (smoked (>or=)20 cigarettes/day, 3 yrs) and nonsmokers, Each subjects was required to perform and incremental exercise test to exhaustion. Tidal volume (V(.T)), respiratory frequency (f), minute ventilation(V(.E)), oxygen uptake (VO(,z)), carbon dioxide output (VCO(,z)), R-value, O(,z)-pulse, blood pressure, electrocardiogram, and heart rate (HR) were recorded at the last minute of each exercise load. The maximal aerobic capacity (VO(,z)max) was determined from the gas exchange data. No differences between smokers and nonsmokers in V(,T), f, V(,E), VO(,z), VCO(,z), R, V(,E)/VO(,z), and V(,E)/VCO(,z) achieved at rest and during each exercies load were found. Pulmonary function test (VC, FVC, FEV(,1), %FEV(,1)/fVE, MMEF) was performed on the two group revealed no statistically different. Cigarette smoking resulted in a significantly higher resting heart rate (p < 0.05) compared with nonsmokers. Additionally, a trend towards a higher exercise heart rate, lower VO(,2) max and O(,2)-pulse max was found during exercise in smokers. In conclusion, cigarette smoking in short duration (3 years) evidently causes long-term deteimental effects on cardiovascular function, including tachycardia and impaired oxygen delivery to exercising muscles. The effects on respiratory function were less striking. These adverse effects on cardiovascular and respiratiory system might be seen in smokers of prolonged smoking history which require further study.