Abstract: Outlines the history, emergence, necessity, challenges, and strategies of the patient safety movement. Explores the challenges for staff working to reduce harm and implement safety improvement in NZ hospitals. Considers medical harm as a persistent and expensive threat to public health. Analyses health policy in the US, England and NZ using the theory of countervailing powers, and a shift from medical to managerial dominance. Reviews theories of accidents and risk, and the safety improvement literature. Provides staff perspectives from NZ by means of interviews with doctors, nurses and managers in two hospitals.