Thirty-two obese patients (Body Mass Index (BMI) = 38.5 +/- 3.7) with obstructive sleep apnoea (the average number of oxygen desaturations per hour of sleep exceeding 4% from the baseline (ODI4) = 38.64 +/- 23.9) underwent a one-year cognitive-behavioural weight reduction programme with a one year follow-up period. The criteria for successful treatment were (i) a decrease in ODI4 to less than 10 and (ii) a decrease in ODI4 that was greater than 50%. Fourteen (44%) patients were considered to be treated successfully at six months. When the patients were grouped according to weight loss 23 patients had lost more than 5 kg; 12 (52%) of them belonged to the group treated successfully. At 24 months, however, only three (9%) patients could be regarded as treated successfully and six patients had been transferred to other treatment modes (Nasal Continuous Positive Airway Pressure (nCPAP) and uvulopalatopharyngoplasty (UPPP)). The changes in weight correlated with the changes in ODI4 (r = 0.47 and 0.63 at the 6-month and the 24-month evaluation, respectively).