The introduction of clinical governance has increased the emphasis placed on measuring the quality of health services. This article addresses the problems associated with assessing the structure, process and outcomes of care of stroke services. The main problem in assessing the structure of stroke services is the difficulty in defining each component and applying criteria which ensure that each component, e.g. stroke unit, stroke physician, is actually in place and meets minimum standards. The structures of stroke services inevitably also vary to meet local needs and conditions. Audits of process and outcome are usually based on aggregated patient data and often include a review of case notes. They are therefore prone to case selection bias, variation in case-mix, measurement error, and random variation. These factors limit the conclusions which can be drawn from most audits. The adverse effects of audit must also be taken into account. It may lead to distortion of health service priorities, divert resources from patient care and encourage individuals responsible for particular services to cheat. Any quality assurance framework should be designed to minimise these effects and to encourage real improvement in the organisation of services and patient care.