The purpose of this study was to determine what factors within a health care organization relate to the occurrence of needlestick injuries (NSIs) among Health care workers (HCW). To do this a systems approach was taken. The overall hypothesis was that factors external to the HCWs were related to the occurrence of NSIs and, therefore, the focus of NSI prevention should be taken off the individual. A mail-out questionnaire was completed by 209 Alberta nurses. From the data generated, a structural equation model was tested which examined factors at many levels of a health care organization as well as those associated with HCWs which may be predictive of the occurrence of NSIs. There was support for the hypothesis that organizational factors, not individual ones, account for the most variance in unsafe needle handling behaviours and NSIs. Discussion centers on the specific factors found to be most related to NSIs and possible human factors interventions.