Aim: The purpose of this study was to investigate the relationship between dyspnea and sleep quality in lung cancer patients. Methods: This descriptive correlational study was carried out between October 2020 and May 2021. The population of the study consisted of all patients who were diagnosed with lung cancer and receiving treatment as inpatients in the Medical Oncology inpatient clinics and outpatient Chemotherapy Unit at İnönü University Turgut Özal Medical Center. The sample included patients who met the inclusion criteria and agreed to participate in the study. The study was completed with 115 patients. The data were collected using a Personal Information Form, the Cancer Dyspnea Scale, and the Pittsburgh Sleep Quality Index. ANOVA, independent samples t-test, Mann-Whitney U test, Kruskal-Wallis Test, Spearman and Pearson correlation coefficients, and linear regression analysis were used to evaluate the data. Results: The mean age of the patients was 60.94±10.62, the mean Cancer Dyspnea Scale score was 27.43±11.71, and the mean total Pittsburgh Sleep Quality Index score was 14.60±3.06. There was a positive correlation between dyspnea scores and sleep quality (p