This study aims to determine the efficacy and tolerability of sibutramine hydrochloride in overweight and obese patients with cardiovascular risk factors. This was a 12-week, open-label, observational trial carried out in primary care settings. Patients' data were obtained from questionnaires received from 153 physicians. A total of 2225 overweight and obese (BMI> or =27 kg/m2) patients received sibutramine in single daily doses of 10 and/or 15 mg. The study population included patients in general good health and with controlled hypertension (41.2%), type II diabetes mellitus (15.6%), hyperlipidaemia (45.5%), and who were chronic tobacco users (smokers) (37.0%). The main outcome measures were changes in body weight, blood pressure and heart rate, and evaluation of reported adverse events. Reduction of body weight of at least >5% from baseline to week 12 was achieved in 2030 (91%) patients and >10% was achieved in 987 (44%) patients. Baseline differences in the percentages of male and female patients, presence or absence of hyperlipidaemia or smoking status did not appear to affect the rate of weight change. Weight loss was less in patients with type II diabetes mellitus and/or controlled systolic hypertension at baseline compared to those patients without these conditions. Mean systolic and diastolic blood pressure and heart rate decreased from baseline to week 12. Overall, sibutramine was well tolerated. In conclusions, treatment with sibutramine resulted in clinically significant weight loss during short-term therapy in obese adults with a range of cardiovascular risk factors..