Background: Obstructive sleep apnea (OSA) is closely associated with metabolic diseases such as hypertension and dyslipidemia. OSA is also frequently found in patients with heart failure. This study aims to determine the prevalence and factors which affect the incidence of OSA in patients with heart failure. Methods: This cross-sectional study was conducted on 70 samples of patients with heart failure in the cardiac outpatient clinic and inpatient ward of the Persahabatan Hospital, Jakarta, Indonesia. Results: Using the Berlin Questionnaire, 42 patients (60%) were found to be at high risk of OSA. Using the Chi-square test, it was found that age (P = 0.988), gender (P = 0.678), body mass index (P = 0.170), neck circumference (P = 0.605), abdominal circumference (P = 0.189), blood pressure (P = 0.922), and smoking (P = 0.678) factors did not have a significant correlation with OSA risk in patients with heart failure. While the tonsil size was found to have a significant correlation (P = 0.005). Conclusions: Patients with heart failure were at risk of having OSA, and tonsil size was significantly correlated with OSA incidence in patients with heart failure. © 2020 Wolters Kluwer Medknow Publications. All rights reserved.