The aim of the study is to estimate the trends in the prevalence of overweight and obesity among Lithuanian adult population and to examine the association of social and health behavior factors with overweight and obesity. Since 1994 five cross-sectional surveys have been conducted among adult population aged 20-64 within the international FINBALT HEALTH MONITOR project. An independent national random sample of 3000 inhabitants of Lithuania was drawn from National Population Register for each survey. The data were collected through mailed questionnaires (covering sociodemographic characteristics, health behaviors, and self-reported height and weight). Overweight was defined as BMI>25 kg/m ( 2 ) and obesity - as BMI>30 kg/m ( 2 ). In 2002 the overall prevalence of obesity was 16% and the prevalence of overweight - 49.1%. Since 1994 both indicators have increased in men while in women the prevalence of overweight has decreased. The prevalence of obesity and overweight increased with age. Obesity and overweight were least prevalent among the highly educated women, but most prevalent among the highly educated men. Women living in cities were less obese and overweight than those living in towns and villages. Obesity and overweight were less prevalent among daily smokers and physically active persons. Women drinking beer at least once a week were less obese and overweight than those who consumed beer more rarely. There was no consistent association between nutrition habits and the prevalence of obesity and overweight. The National obesity control program aimed at promotion of healthy nutrition and physical activity should be elaborated in order to decrease the prevalence of obesity and overweight in Lithuanian population.