Aims: To determine the relationship of body mass index (BMI) and abdominal adiposity with current educational level among the adult population of Iran. Methods: A nationwide cross-sectional survey was conducted from December 2004 to February 2005. The selection was conducted by stratified probability cluster sampling through household family members in Iran. Weight, height, waist circumference (WC) and educational level of 89,404 men and women aged 15-65 (mean 39.2) were recorded. Four classes of BMI (<18.5,18.5-24.9, 25-29.9, and >= 30) and three educational levels (primary or below, secondary, and matriculation or above) were used. Abdominal adiposity was defined as WC >= 102 cm in men and >= 88 cm in women. Results: Thirty-two percent of men and 32.5% of women were overweight (BMI=25-29.9), and 10.9% of men and 24.6% of women were obese (BMI >= 30). The prevalence of obesity and abdominal adiposity decreased with increase in educational level in both men and women. In women, overweight was decreased slightly with increase in educational level, while in men it increased. The prevalence of obesity according to educational level was as follows for women: primary or below -28.1%; secondary -18.7%; matriculation or above - 13.0%. In men, these figures were 12.2%, 9.9%, and 10.0%, respectively. Conclusions. Higher education level is associated with a lower prevalence of obesity and abdominal adiposity in both men and women in Iran.