Fifty registered nurses were interviewed to determine how nurses view routine post anaesthetic observations (RPAOs). A structured interview established whether nurses routinely carry out post anaesthetic observations and if they believe that routine observations are part of ward procedure or hospital policy. Nurses' beliefs about the necessity for performing these observations and the rationales they use to justify them were also explored. The results show that all the nurses sampled interpreted RPAOs to mean half hourly vital sign measurements for four hours, and believed that the regimen was prescribed by ward or hospital policy. Many believed that this frequency was necessary to detect complications of surgery or anaesthesia. A small number of nurses felt obliged to comply with perceived hospital policy despite an assessment that it was unnecessary. Procedure-driven assessment and tradition rather than individualized patient assessment appear to be directing post operative nursing actions.