Although regular exercise reduces the risk of cardiovascular diseases, post-exercise recovery is thought to be a vulnerable phase for an increased susceptibility to sudden cardiovascular events. Cigarette smoking has been demonstrated to amplify sympathetic activation and cardiovascular stress. Paradoxically, many smokers tend to smoke immediately after leisure-time physical activity or exercise. PURPOSE: We tested the hypothesis that smoking immediately after exercise would deteriorate autonomic and hemodynamic recovery following an acute bout of aerobic exercise compared with the sham smoking control. METHODS: Ten healthy male smokers (age=21±3yrs; BMI=24.7±3.9kg/m²) participated in two trials in a randomized order: 1)cigarette smoking immediately after exercise (SM), 2)sham cigarette smoking after exercise (SHAM). All subjects exercised on a treadmill at a moderate intensity (40-60% of heart rate reserve) for 30 minutes and smoked one cigarette (0.6mg nicotine) or sham cigarette immediately after exercise. We measured heart rate, brachial and central artery blood pressures, rate-pressure product, carotid-femoral pulse wave velocity (PWV), brachial artery flow-mediated dilation (FMD), and heart rate variability time domains. All variables were measured at baseline and at 10 minutes and 30 minutes after exercise, except for FMD measured at baseline and 30 minutes after exercise. RESULTS: Rate-pressure product was significantly higher in the SM trial compared to the SHAM trial (interaction effect; p=0.008). Central systolic and diastolic blood pressure increased in the SM trial (interaction effect; p=0.026, p=0.006, respectively). PWV was higher post-exercise in the SM trial, but this did not reach statistical significance (p=0.116). FMD increased only in the SHAM trial (p=0.008). SDNN decreased from baseline more so in the SM trial (SM:51.5±24.5ms to 23.6±15.7ms to 36.3±18.9ms) compared with the SHAM trial (SHAM:56.8±28.1ms to 43.1±17.2ms to 50.8±22.8ms)(p=0.041 for interaction). CONCLUSION: Cigarette smoking immediately after exercise deteriorated autonomic and hemodynamic recovery in smokers, suggesting that smoking immediately after leisure-time physical activity or exercise should be avoided to reduce in the susceptibility of sudden cardiovascular events.