This paper reports the distribution and determinants of body mass index (BMI) and obesity in Tirana City (Albania). Cross-sectional survey conducted in mid-2001. Tirana City. One thousand one hundred and twenty adults aged 25 years and over (response rate 72.7%), selected using multi-stage cluster sampling. Over three-quarters of male and female respondents had an excess body weight. The overall population prevalence of obesity in Tirana was estimated to be 22.0% in men and 30.9% in women. Obesity affected both genders (age-standardised prevalence in males 22.0%, females 30.9%; age-adjusted odds ratio (OR) 1.89; 99% confidence interval (CI) 1.33-2.67) and all age groups, but most particularly middle-aged women. The age-standardised overall prevalence of central obesity was 21.6% in men and 29.4% in women (age-adjusted OR 1.58; 99% CI 1.11-2.25), increasing with age (P<0.01). In women, the likelihood of being obese was inversely related to educational achievement (trend P=0.001) and alcohol consumption (trend P=0.009). Income, smoking and leisure-time physical activity were not associated with obesity. Excess weight and obesity are major public health problems in the adult population of Tirana, but most particularly in middle-aged women. The high obesity prevalence observed along with the recent decrease in physical activity, dietary changes and increase in smoking prevalence make it probable that there will be substantial increases in many non-communicable diseases in Albania in the coming decades. Health promotion strategies are needed that prevent excess weight gain in the Albanian population.