OBJECTIVES: To investigate the relationship between mucociliary transport and physical activity in daily life (PADL) in smokers and nonsmokers. METHODS: Fifty-two current smokers were submitted to assessment of mucociliary transport (Sacharin Transit Time, STT), carbon monoxide levels in the exhaled air, lung function and smoking history. In addition, subjects kept a pedometer worn at the waist for six days in order to determine their level of PADL (steps/day). The tests were also performed on 30 matched healthy nonsmokers who served as control group. RESULTS: Light smokers (≤15 cigarettes/day) had a STT of 9 (7-11) min (median [confidence interval]), which was similar to nonsmokers (8 [8-11]min; p=0.8). Both moderate (16-25 cigarettes/day) and heavy (>25 cigarettes/day) smokers had significantly higher STT (13 [11-17] min and 13 [10-21] min, respectively) than nonsmokers and light smokers (p<0.05 for all). There was no difference in the number of steps/day between any of the groups (p>0.05 for all). In the general group of smokers, STT was not significantly correlated with PADL, pack/years index, years of smoking or age (r<-0.23; p>0.09 for all). There was significant negative correlation between STT and PADL only in light smokers (r=-0.55; p=0.02) and nonsmokers (r=-0.42; p=0.02), but not in moderate and heavy smokers. CONCLUSION: In light smokers and non-smokers, better mucociliary function is associated to higher daily physical activity level, as opposed to the decreased mucociliary function observed in smokers, i.e., those with moderate and heavy cigarette consumption.