Aims: Sleep disorder is common among patients with renal disease in its last phase. Progressive musclerelaxation is a method which has been designed to reduce tension and anxiety. The present study wascarried out to determine the effect of progressive muscle relaxation on sleep quality of patientsundergoing hemodialysis.Methods: This is a quasi-experimental study with one-group, before and after design. Using purposivesampling method, 39 patients were selected. These patients were being treated with maintenancehemodialysis in hospitals affiliated with Shahid Beheshti University of Medical Sciences in 2010. Sleepquality of samples was assessed by Pittsburgh Sleep Quality Index (PSQI). Progressive muscle relaxationwas trained to patients in three sessions. They were also asked to do relaxation practice for a month, twicea day (once during the day and once before going to bed at night), and fill in the relaxation form aftereach practice. Afterwards, sleep quality of patients before and after relaxation were compared. To analyzethe statistical data, paired t-test and wilcoxon test were used.Results: The mean of samples’ sleep quality total score after relaxation was significantly lower thanbefore relaxation (p