INTRODUCTION: The aim of this study was to investigate the relationship between pre-operative ruminative thought style and anxiety level and sleep quality in patients receiving inpatient treatment in the Otorhinolaryngology Clinic. METHODS: The descriptive, cross-sectional, and correlational study was conducted between May 01 and October 01, 2024, in the otolaryngology clinic of a public hospital. Sociodemographic data form, ruminative thinking style questionnaire (RTSQ), Beck Anxiety Inventory (BAI), and Richard-Campbell Sleep Questionnaire (RCSQ) were administered to the participants. Results: The mean age of the patients who participated in our study was 40.75±16.26 years. The mean score of the RTSQ was 77.234±1.40, the mean score of BAI was 12.424±0.61 and the mean score of the RCSQ was 52.104±1.44. RTSQ was found to have a positive relationship with the BAI (r=0.434, p<0.05) and a negative relationship with RCSQ (r=-0.201, p<0.05). A negative relationship was found between the BAI and RCSQ (r=-0.304, p<0.05). Among the patients who had negative thoughts about the surgery, 14.7% stated statements related to fear of death. DISCUSSION AND CONCLUSION: This study revealed that as ruminative thinking increased, anxiety levels increased and sleep quality decreased in pre-operative patients in a surgical clinic. Future studies can be planned on the effect of rumination on the recovery process, demand for medical treatment for pain, and length of hospitalization of patients hospitalized in a surgical clinic.