© 2016 Wiley Periodicals, Inc. To more precisely evaluate the effects of nurse staffing on hospital-acquired pressure injury (HAPI) development, data on nursing care hours per patient day (NCHPPD), nursing skill mix, patient turnover (i.e., admissions, transfers, and discharges), and patient acuity were merged with patient information from pressure injury prevalence surveys that were collected annually for the Military Nursing Outcomes Database (MilNOD) project. The MilNOD included staffing and adverse events from 56 medical-surgical, stepdown, and critical care units in 13 military hospitals over a 4-year-period. Data on 1,643 patients were analyzed with Cox proportional hazards models and generalized estimating equations. Staffing was not associated with pressure injuries in stepdown or critical care patients. However, among the 1,104 medical-surgical patients, higher licensed practical nurse (LPN) nursing care hours per patient day (NCHPPD) 3 days and 1 week prior to the HAPI discovery date were associated with fewer HAPI (HR 0.27, p <.001), after controlling for patient age, Braden mobility score, and albumin level. Neither total staff number, nor RN NCHPPD, nor the proportion of staff who were RNs (RN skill mix) were associated with HAPI. These findings suggest that on military medical-surgical units, LPNs play a major role in HAPI prevention. Although the national trend in acute care is to staff hospital units with more RNs and patient care technicians, and fewer LPNs, hospitals should reconsider LPNs as valuable members of the nursing care team. © 2016 Wiley Periodicals, Inc.