Many patients with obstructive sleep apnea (OSA) do not have sleepiness and adherence to nasal continuous positive airway pressure (nCPAP) is unknown when this treatment is primarily recommended for a cardiovascular concern. The aim of this study was to determine the adherence to nCPAP in patients with coronary artery disease (CAD) and OSA without sleepiness. nCPAP was recommended in 75 patients with CAD and OSA, 29 without and 46 with sleepiness. The daily use of nCPAP and changes in sleepiness (Epworth Sleepiness Scale), in other OSA symptoms and in SF-36 quality-of-life questionnaires were evaluated at 1 yr of follow-up. Sixty-seven patients (89%) were still using nCPAP at the end of follow-up. The absence of sleepiness at diagnosis did not imply a greater number of nCPAP refusals and nCPAP adherence was similar in both groups, 5.1 (1.5) h in patients without versus 5.4 (1.6) h in patients with sleepiness. In patients with sleepiness at diagnosis, the use of nCPAP was associated with reduced sleepiness and improvement in the OSA symptoms and quality-of-life questionnaires; in contrast, only the symptoms questionnaire improved in patients without sleepiness. In conclusion, in our experience adherence to nCPAP treatment in patients with CAD and OSA is not influenced by the absence of sleepiness.