Much has been written about quality in patient care and clinical support services, but very little about the quality of purchasing. This paper gives an overview of quality issues in purchasing, and offers guidelines and practical steps for purchasers to improve service quality--both their own and their providers'. It defines quality in purchasing and considers how purchasers can influence markets and work with providers to improve health services quality. The paper gives practical guidance for improving quality, which recognises the limited resources and skills which purchasers have for the task. It addresses some issues raised by purchaser/managers: How does a purchasing organisation measure and improve quality? Is there a better way of specifying and monitoring quality than the "shopping-list of standards" approach--what should be asked of providers? How can information about clinical quality, outcome and costs, be obtained in a form in which reliable comparisons can be made? Is quality accreditation or registration a good predictor of future quality?