Given its potential to impact physical and mental health, sleep quality is one of the most significant clinical outcomes among hemodialysis patients. Patients undergoing hemodialysis are required to adhere to an intricate treatment plan that consists of regular hemodialysis treatments, dietary and fluid restrictions, and a multi-drug regimen. Investigate the relationship between adherence to a therapeutic regimen and sleep quality among chronic renal failure patients undergoing maintenance hemodialysis. A descriptive correlational research design was followed. The study was conducted at the hemodialysis units in Hafr Albatin City, specifically at Hafr Albatin Central Hospital and King Khaled Hospital, Saudi Arabia. A convenience sample of 100 adult patients was selected for the study. The Hemodialysis Patients Adherence Questionnaire and Pittsburgh Sleep Quality Index were utilized to collect the data in 5 months from September 20, 2023 to February 15, 2024. The study revealed that more than half of the studied patients adhered to the therapeutic regimen, while (46%) did not adhere to it. More than half of the patients had poor sleep quality and were nonadherent to diet and fluid restrictions. Overall adherence score is negatively correlated with the global sleep quality score (r = -0.368, p < 0.001), indicating that poorer sleep quality is associated with lower overall adherence to the therapeutic regimen. While a significant proportion of the patients demonstrated adherence to overall therapeutic regimens, including dialysis sessions and medication intake, there was notable nonadherence to fluid and diet restrictions. Poor sleep quality, prevalent among two-thirds of the participants, correlates negatively with adherence to therapeutic regimens.