OBJECTIVE This study aimed to evaluate the prevalence of overweight and obesity derived from measured data of weight and height in a cross-sectional sample of adolescents in the Italian region of Lazio and to analyse their association with different socio-demographic factors. METHODS The study was conducted in a representative sample of 15-16-year-old adolescents recruited in secondary schools between December 2011 and May 2012. 369 adolescents were investigated. Body weight, height and waist circumference were measured. The BMI of each subject was calculated, and the prevalence of overweight and obesity was determined by age and sex using the IOTF reference values and WHO growth standards. Waist circumference/height ratio (WC/Ht) was calculated and the subjects were classified using the cut-off of 0.5: WC/Ht≥0.5 and WC/Ht<0.5. Selected socio-demographic characteristics were assessed via questionnaire. RESULTS The percentages of overweight and obesity were high, 15.4% and 7.9%, respectively, with significant difference between males and females (19.1% vs. 12.6% for overweight and 11.1% vs. 5.3% for obese) using the IOFT reference. The ratio WC/Ht≥0.5 was observed in 12.7% of the sample (all the obese and 29.8% of the overweight subjects). Multiple logistic regression analysis indicated that gender, school municipality, mother's employment status, and family structure had a significant effect on ponderal status (overweight/obesity vs. normal weight). CONCLUSIONS These findings show a high prevalence of body weight excess associated with socio-demographic factors in the Italian sample investigated, and the need for effective public health interventions to combact obesity with particular attention to disadvantaged adolescents.