This article reviews the general issues in valuing health states for use in cost-effectiveness analysis and the specific issues considered by the National Institute for Health and Clinical Excellence (NICE) in its recent review of the methods of technology appraisal. The general issues are how to describe health, how to value health and who should provide the values for health. The specific issues considered by NICE included whether and what should be the reference-case instrument, what to do when there are no data using the reference-case measure, what to do when the reference-case measure is not suitable and how to judge when it is not suitable, how to review and synthesize data, and how to incorporate health-state utility values into cost-effectiveness models.