High patient turnover (patient throughput generated by admissions, discharges, and transfers) contributes to increased demands and resources for care. We examined how the relationship between registered nurse (RN) staffing and failure-to-rescue (FTR) varied with patient turnover levels by analyzing quarterly data from the University HealthSystem Consortium. The data included 42 hospitals, representing 759 nursing units and about 1 million inpatients. Higher RN staffing was associated with lower FTR. When patient turnover increased from 48.6% to 60.7% on nonintensive units (non-ICUs), the beneficial effect of non-ICU RN staffing on FTR was reduced by 11.5%. RN staffing should be adjusted according to patient turnover because turnover increases patient care demand beyond that presented by patient count, and outcomes may be adversely affected.