Staffing needs in an ambulatory oncology infusion setting can be challenging. The workload of nurses and time required to provide patient care are increasing. With the addition of new targeted therapies and complicated treatment regimens, increased patient acuity should be considered when determining daily staffing. This article describes the development of an acuity tool based on the complexity of patient treatments. The first part of the process focused on development of the tool and data collection during a two-month period to assess the complexity of patient treatments. The second part used the tool to determine daily staffing for infusion rooms. The tool provides a better representation of acuity in infusion rooms by connecting the complexity of patient treatments with staffing on a daily basis. In addition, the tool is easily adaptable to changing oncology treatment regimens because it provides a basis for assessing treatment complexity in the infusion room.