AIMS: To determine how the prevalence of Type 2 diabetes mellitus has changed in Tirana, the capital of Albania, over 20 years. METHODS: Cluster sampling was used to select 700 households including 1540 adults 25 years of age and over in Tirana City, Albania in 2001. RESULTS: Of 1540 potential subjects, 1120 participated (response rate 72.7%). Using the 1985 WHO criteria to provide comparability with earlier data, the overall prevalence of Type 2 diabetes mellitus in the age group 25+ was 6.3% (95% confidence interval 4.8-7.7); 6.9% (4.8-9.1%) male; 5.6% (3.8-7.5%) female. The age-adjusted prevalence in those aged 25+ was 5.4%. Of respondents, 3.4% were known to have diabetes, and 2.9% were newly identified through the survey. The prevalence of diabetes increased with age, although among men there was a slight decline after age 65. Impaired glucose tolerance was found in a further 2.9% of respondents, again increasing with age. The prevalence of diabetes has increased significantly since 1980, doubling in the age group 50+. Use of the 1999 WHO diagnostic criteria produces a higher unadjusted prevalence, at 9.7% (8-11.4%). In a logistic regression model, obesity and family history were independent determinants of the probability of having diabetes. Among those known to have diabetes, control was poor. CONCLUSIONS: The prevalence of diabetes in Albania has increased rapidly, consistent with what has been seen in other countries undergoing rapid modernization. It is likely to increase further in the future, with important implications for health policy.