Fifty unselected consecutive patients with obstructive sleep apnea syndrome (OSAS) diagnosed by nocturnal recordings of respiration movements by a static charge sensitive bed (SCSB) and oximetry, alone or combined with polysomnography, were studied. Renewed SCSB-oximetry recordings evaluated treatment. Six months after surgery, 30 of 50 were classified as responders. Twenty-one months after surgery, 19 of 49 were responders. Patients who relapsed showed a significant increase in mean body mass index (BMI). Four years after surgery, 24 of 48 patients were responders. Preoperative BMI was significantly lower in the responder group. Subsequent treatment was required in 15 nonresponders. There was no correlation between patients' subjective improvement and objective results. The study resulted in the following conclusions: 1. The responder rate to UPPP in unselected patients is low. 2. Obesity and high indices of nocturnal respiratory disturbance are negative predictors. 3. The patients' subjective recovery alone must not be used for postoperative evaluation. 4. With regular follow-up and the use of the treatment alternatives available today, the majority of OSAS patients can receive effective treatment.