Overweight and obesity are seen to be major risk factors for costly chronic diseases and can worsen other chronic conditions, leading to important health care resources absorption. There is evidence that health care resources use is associated with the severity of obesity expressed as body mass index (BMI). OBJECTIVES To examine direct and indirect costs per overweight and obese subject and to investigate the association between BMI and the costs of caring for overweight and obese subjects. METHODS The first 10 overweight and obese subjects attending 52 medical offices in Italy were enrolled. Medical and economic information was retrospectively collected using an electronic questionnaire. The societal perspective was adopted. Costs considered were direct (visits, diagnostics, drugs, other therapies, hospitalisations) and indirect (working activity reduction or abandon) and refer to a 6-months period. The association of costs with BMI was explored using parametric and non parametric tests as appropriate. All costs are in Euro year 2001 (1 Euro=0.9 US$). RESULTS The mean age of the 367 subjects enrolled was 43.18 (±12.9) and the mean BMI 35.34 (±6.72). 73.6% of the subjects were females, and 77.7% obese (BMI>30). The mean 6-months health-care cost estimated was 855 Euro per subject. Hospitalisation was the health-care cost driver (64% of the total), followed by drugs (7%), visits and diagnostics (6% each). 16% percent of the sample reduced working activity by 35% on average. The cost of care for an overweight subject was significantly lower compared to an obese (685 vs 917 Euro, P=0.011). BMI was associated with direct costs (P=0.004) and with work abandon or reduction (p=0.001). CONCLUSIONS The present study gives the opportunity to understand how health care expenditure vary across a wide range of BMI values in Italy and this could have important implications for targeting preventive and weight reduction interventions.