The diagnosis of breast cancer is experienced as a moment of immense anguish, suffering, anxiety and stress. This mental state influences the quality of sleep as well as quality of life. Objective: To verify the benefits of Reiki as an integrative and complementary practice in the levels of stress, anxiety, quality of sleep and life of mastectomized patients. Method: case study with 9 mastectomized patients in chemotherapy and or radiotherapeutic treatment and physical therapy treatment at Emescam Clinical School of Physiotherapy. The patients were allocated to two groups, group A (Reiki application), group B (Reiki simulation). The two groups received 20 minutes of session, twice a week for 8 sessions. The following questionnaires were used: socioeconomic-demographic and clinical, welfare scale, PSS-10, Beck Anxiety Inventory (BAI), SF-36, PSQI-BR, and vital signs ( FR, FC, PA, Tax). Result: No differences were observed in heart rate, respiratory rate and temperature between groups. In the well-being, a variation from 8 to 4.5 was observed in group B, which showed worsening of well-being. There was a mild level of anxiety in the eighth session in both groups (11×15), without stress oscillations, in group A (20-22) and group B (16,5-15). As sleep, both groups were above the score, (10×9). In the group without Reiki, there was a worsening of quality of life (92-88.5). Conclusion: Reiki did not influence levels of stress, anxiety, quality of life and sleep in mastectomized women.