PURPOSE:Auto-titrating continuous positive airway pressure (APAP) is an effective treatment for obstructive sleep apnea/hypopnea syndrome (OSAHS). We investigated whether a single group education session on APAP therapy is effective in promoting adherence among patients with OSAHS. METHODS:This prospective, randomized, controlled, parallel group study included patients newly diagnosed with OSAHS who met criteria for APAP therapy. Patients were randomized into a study group and a control group. All patients in the study group were assigned to a single group education session, 1 month after beginning APAP therapy. RESULTS:We evaluated 146 patients. The median percentage of APAP usage days was 88.3 %, with a median duration per day of use of 6.02 h; 59 % were classified as adherent. Overall, no significant difference in adherence was seen between the study and the control groups. Analyzing patient subgroups, the group session significantly improved APAP adherence among males and patients who were younger (<65 years old), obese (BMI ≥ 35 kg/m(2)), non-sleepy (Epworth sleepiness scale ≤ 11), smokers or past smokers, had hypertension or nocturia and those with non-severe OSAHS. CONCLUSION:To maximize the impact of group education sessions and, by that, saving resources, it may be important to select patients likely to benefit from these sessions.