Most Australian public health-care services have established a range of initiatives designed to help 'protect' nurses and midwives from patient and visitor assault (PVA); however, few studies have specifically examined their effectiveness. The present study is part of a larger survey that explored nurses' and midwives' experiences of PVA using the Department of Human Services, Victoria (2007) definition of occupational violence and bullying. Participants were asked about the presence of 'protective' factors in their workplace and the importance of having these factors to prevent and manage workplace aggression. Binary logistic regression was applied to ascertain the association between 'protective' factors and the occurrence of PVA, with adjusted odds ratios and their reported 95% confidence intervals for ascertaining the significance of the associations. The study found more 'protection' from assault when there was a high standard of patient facilities, sufficient staffing, effective enforcement of policies, and when staff were provided with personal protective equipment. Working in private health care, and being a registered nurse, also conferred 'protection'. A higher occurrence of staff assault was associated with specific clinical settings, and being on rotation and on night duty. Findings point to important insights into factors associated with 'protection' for PVA.