Objectives: the aim of this study is to determine the effect of progressive muscle relaxation on sleep quality in patients with chronic heart failure. Design: this non-blinding randomized controlled trial is done in CCU wards of Fatemeh Zahra Hospital in Sari. Study population: patients with chronic heart failure. Inclusion criteria: age older than 18 yearsold; NYHA class 2 and 3; at least 3 months past history; Pittsburgh score of 5 or higher; no consumption of sedatives, antidepressants and antihistamines. Exclusion criteria: no cooperation; consumption of sedatives; not doing relaxation more than 10% (6 times ) during the study; be candidate for cardiac invasive procedures. Sample size: 90 patients are divided into two groups: intervention and control. Intervention: progressive muscle relaxation is taught during three sessions in each patient. The first session is hold after stabilization of clinical signs, for 30 minutes. The second session is done at the evening of the same day, for 15 minutes. The third session is hold the next morning, for 15 minutes. After obtaining properly feedback, relaxation educational booklet associated with a CD and an event recording check list are delivered to patients and asked them to do this technique twice daily (once in the morning and once at night before sleeping), for one month . In order to evaluation,telephone follow up of patients is done by researcher weekly. The patients of control group will receive the usual care.