Introduction: The sleep quality of patients with heart failure is important for the protection of physiological and psychological health. Objective: This study was conducted as a descriptive study to examine the sleep quality of patients with heart failure and the factors affecting sleep quality. Method: The research is descriptive type, which was conducted with 121 heart failure patients in the cardiology service of a university hospital between November 2019 and February 2020. Research data were collected using the Patient Identification Form and the Pittsburgh Sleep Quality Index. The questionnaires were collected by the researcher by interviewing the patients. The data were evaluated in the SPSS 16.0 package program on the computer, and arithmetic means, percentage, significance test of the difference between two means, analysis of variance, correlation, and Kruskal-Wallis tests were used for analysis. Results: The mean age of the patients participating in the study was 64.41 ± 12.52. Of the patients, 55.3% were women, 63.6% were married, and 50.3% had a diagnosis of hypertension. It was determined that the majority of the patients (61.9%) had 5-7 hours of sleep per day, and the mean PSQI score of the participants was 14.16 ± 2.46. When the sub-dimensions of PSQI were evaluated, the worst was determined as “daytime dysfunction” and the best was determined as “using sleeping pills”. It was determined that the sleep quality of female, married, chronically ill patients with heart failure who had a sleep habit of fewer than 5 hours and more than 7 hours were worse than the others and there was a statistically significant difference in sleep quality (p<0.05). Conclusion: In this study, it was determined that the sleep quality of patients with heart failure was poor. Therefore, planning nursing care and practices that will increase sleep quality can positively affect the psychological and physiological well-being of patients with heart failure.