The measurement of health outcomes is central to all evaluative studies. Clinical practice too, is shaped by the need to monitor health status, and changes in health status. A prime requirement in most studies is the capacity to represent benefits (or disbenefits) in terms of a single, aggregate value. This property is typically absent from profile measures that characterise health status in terms of separate dimension scores. EQ-5D is a generic measure that yields a single index value for health status based on self-reported problems on each of 5 dimensions - mobility, self care, usual activity, pain/discomfort, anxiety/depression. Utility weights for each of 245 health states are available. EQ-5D is one of a handful of measures recommended by the Washington Panel on Cost-Effectiveness. Elsewhere EQ-5D has received official sanction under the European Commission BIOMED programme, and has been incorporated in the English National Health Survey. EQ-5D has rapidly been assimilated into clinical trials by many of the major pharmaceuticals. This Workshop is designed to provide an overview of the development of EQ-5D, outlining the research programme undertaken by the EuroQoL Group over the past 10 years.; to report on its use in clinical and economic evaluation; and to detail its international take-up. It is expected that Workshop attendees will be primarily researchers and analysts concerned with clinical and economic evaluation, particularly where international collaboration is involved. Thus far EQ-5D has been translated into more than 25 languages. Participation in the Workshop should provide sufficient exposure to enable all attendees to reach a balanced conclusion regarding the usefulness of EQ-5D.