The IPSS straining scores of the non-smokers were significantly lower than those of the smokers (1.710 ± 1.690 vs. 2.600 ± 1.902, p=0.029), and the non-smokers' scores for weak stream, voiding subscore, and total score tended to be lower than those of the smokers (weak stream 3.350 ± 1.798 vs. 3.980 ± 1.291, p=0.058; voiding subscore 7.510 ± 4.426 vs. 9.320 ± 4.322, p=0.057; total score 17.110 ± 8.386 vs. 20.400 ± 7.724, p=0.060). In the pressure flow study, there were negative correlations between duration of smoking and strong desire to void (SDV), and between urgency and bladder volume at the initial detrusor overactivity (DO) (SDV: correlation coefficient -0.314, p=0.013, Fig. 1A; urgency: correlation coefficient -0.349, p=0.008, Fig. 1B; bladder volume at initial DO: correlation coefficient -0.417, p=0.021, Fig. 1C). Maximum cystic capacity (MCC) tended to be negatively correlated with the duration of smoking (correlation coefficient -0.227, p=0.055).Serum PSA level and serum CRP level was positively correlated with the duration of smoking (serum PSA level: correlation coefficient 0.212, p=0.047, serum CRP level: correlarion coefficient 0.216, p=0.049). We next focused on the former smokers and examined the relationship between smoking cessation and clinical parameters. The duration of smoking cessation was significantly negatively correlated with the magnitude of chronic prostatic inflammation (correlation coefficient −0.253, p=0.027, Fig. 1D). In the pressure-flow study, the duration of smoking cessation was positively correlated with urgency and MCC (urgency: correlation coefficient 0.286, p=0.030, MCC: correlation coefficient 0.241, p=0.050). SDV and BOOI tended to be correlated with duration of smoking cessation (SDV: correlation coefficient 0.241, p=0.051, BOOI: correlarion coefficient -0.260, p=0.062).