The rate of dependence among ever-users of a drug indicates the risk of developing dependence once an individual has been exposed to the drug. This is the first study to investigate 12-month tobacco dependence (TD) among ever-smokers in a community-based population. Analyses were based on two national studies of representative samples aged 18-64 in 1984 (n=5,025) and in 2001 (n=6,275), conducted with household visits and face-to-face interviews. The rates of 12-month TD among ever-smokers in men showed no significant difference between 51.6% in 1984 and 50.6% in 2001. On the contrary, the rates in women significantly increased from 33.3% in 1984 to 52.8% in 2001. After adjusting for the sociodemographic variables, 'male gender' was significantly associated with 12-month TD among eversmokers in 1984, but not in 2001. 'Unmarried' was significantly associated in 2001 but not in 1984. 'Alcohol dependence' was the only psychiatric disorder associated with 12-month TD in both study years. In conclusion, 12-month TD was found in about 50% of ever-smokers, and gender differences between the rates of 12-month TD which was observed in 1984 disappeared in 2001. Individuals with 12-month TD showed higher comorbidity with alcohol dependence than ever-smokers without TD.