Abstract : This integrative literature review aimed to understand the meaning of patients’ acuity, patient acuity tool, and to investigate the effectiveness of applying patients’ acuity tool on nursing and patients’ outcomes. A search protocol was implemented using five electronic databases from January 2000 to December 2016. Thirty-nine articles were included in this paper. The findings of this integrative review showed that patient acuity tool serves as a document tool and the managers’ voice for important staffing decisions as recruitment, assignment distribution and employing new staff. The tool can assist nursing staff, and it is very important for the patients’ outcomes like the quality of care and patient safety. The patient acuity tool is a major asset for nursing management, staff, and most important for the patient. Nursing assignment, nurse s’ satisfaction, nursing workload acuity, patient acuity tools, patient classification systems, and patients’ outcomes