Background : Most breast cancer patients are suggested to undergoing of chemotherapy. One of the effects of chemotherapy is poor sleep quality. Someone suffering from sleep disorders is potential to suffer from fatigue, depression, and anxiety. The Implementation of the Prophet’s sunah before sleeping gives the body a positive effect. Objectives: The study aimed to determine the effect of the implementation of Prophet’s sunah before sleeping to the quality of sleep for breast cancer patients Methods : The study applied the Quasi Experiment pretest-posttest with intervention and control group design. The collected samples are 26 breast cancer respondents with Purposive Sampling technique. Sleep quality was assessed by using the Pittsburg Sleep Quality Index. The intervention of the Prophet’s sunah was done before sleeping for 7 days. Sleep quality data were analyzed by using the Independent t-test. Result : Sleep quality controls group pretest 9.83 and posttest 11.83, sleep quality interventions group pretest 12,93 and posttest 7,00. The posttest results of the two groups with p value = 0.003. Conclusion : There was a influence after being implemented the Prophet's sunah before sleeping to the sleep quality of breast cancer patients Keywords : Breast Cancer, Chemotherapy, Prophet’s Sunah, Sleep