We performed smoking cessation using varenicline on 230 smokers from August 2008 to March 2012. The study participants consisted of 167 men (72.6%) and 63 women (27.4%) with a mean age of 45.7±12.7 years, ranging from 23 to 92. The mean number of cigarettes smoked daily was 25.7±9.9, ranging from 7 to 60 cigarettes total. The mean duration of smoking was 25.1±11.5 years, from 5 to 70 years. The mean amount of exhaled carbon monoxide (CO) before treatment was 19.6±10.1 ppm, from 0.7 to 62 ppm. The mean Brinkman index was 632.1±367.4, from 200 to 2,200. The average Tobacco Dependence Screener (TDS) score was 7.75±1.57. The most frequently observed treatment-emergent adverse event was nausea, occurring in 23.5% of participants. The average abstinence rate was 72.2% (166/230), 76.0% (127/167) among male participants and 61.9% (39/63) among females. Statistically lower abstinence rates were seen in participants with mental disease and females in their twenties. The logistic regression analysis statistically revealed that independent factors correlated with a lower abstinence rate were females and youths. The long-term abstinence rate at 48 weeks was 49.7% (84/169), 51.7% (62/120) among male and 44.9% (22/49) among females.