OBJECTIVE: Obesity and diabetes are increasing problems worldwide. Therefore, new data on these issues are of importance. Here, we publish data on body mass index (BMI) and prevalence of diabetes of type 2 in Iceland. MATERIAL AND METHODS: Mean BMI (kg/m2), prevalence of diabetes type 2 and obesity in people aged 45-64 years were evaluated from 1967 to 2007. Data on type 2 diabetes was based on four population Icelandic Heart Association studies (newest the REFINE (The Risk Evaluation For INfarct Estimates) Reykjavik study from 2006) with total of 17.757 individuals. Data on BMI was in addition based on three further studies, total 20.519 individuals. The same estimates were then performed for 25-84 year old people in the years 2004-2007. These were based on data from the REFINE Reykjavik study 2.410 individuals and the AGES Reykjavik study 3.027 individuals and. RESULTS: In the years 1967-2007 mean BMI increased by 2 units in both genders (45-64 year) and the prevalence of type 2 diabetes doubled in men, while the increase in women was 50%. In the years 2004-2007 the prevalence of diabetes type 2 in 25-84 year old people was 6% in men and 3% in women and the prevalence of obesity was 23% in men and 21% in women. CONCLUSIONS: Mean BMI is increasing in Iceland, especially after 1980. Prevalence of diabetes coincides with increasing body mass index.