['Recent data suggest that obstructive sleep apnea (OSA) is an important contributor to severe uncontrolled asthma.', 'To investigate the clinical characteristics, asthma control, and asthma-related quality of life in adult patients with asthma at a high risk for OSA.', 'A total of 217 patients with asthma who visited our tertiary-care clinic were randomly recruited. They completed the Berlin questionnaire, which screens for OSA risk, a quality-of-life questionnaire for adult Korean patients with asthma (QLQAKA), and underwent an asthma control test (ACT). Fraction of exhaled nitric oxide (FeNO), lung function, blood lipid profiles, and body composition were evaluated.', 'The mean age was 58.4 ± 15.4, and 91 (41.9%) were male. Eighty-nine subjects (41.0%) were classified as high risk for OSA from the Berlin questionnaire. Patients with a high OSA risk were significantly older, had a higher prevalence of hypertension, higher BMI, non-atopic predisposition, and longer asthma treatment duration in the baseline clinical characteristics. The high OSA risk group had a lower ACT score than the low OSA risk group, but it was not statistically significant (20.9 ± 3.6 vs 21.5 ± 3.3, P\xa0= .091). The QLQAKA score was significantly lower in the high OSA risk group compared with the low OSA risk group (64.4 ± 10.9 vs 68.1 ± 11.1, P\xa0= .026), especially in the activity-domain (P\xa0= .005). The FeNO was not significantly different between the 2 groups.'] Is obstructive sleep apnea associated with reduced quality of life in adult patients with asthma?