This descriptive study determined the prevalence of underweight, overweight and obesity among 752 high-school girls aged 14–18 years in Sistan va Baluchistan province, Islamic Republic of Iran. Using the Centers for Disease Control and Prevention body mass index percentiles, the prevalences of underweight, overweight and obesity were 16.2%, 8.6% and 1.5% respectively. These rates were similar to the ones obtained using World Health Organization, First National Health and Nutrition Examination Survey, and International Obesity Task Force criteria. The frequency of underweight in high-school girls in this province is higher than most countries and other parts of the Islamic Republic of Iran.