Most of the recent work on performance indicators has concentrated on the provision or activities of health services rather than on their impact on the patients and populations who use them. Although the precise relationship between treatment and outcome is often unclear, simple examination of routinely available data can show whether mortality and morbidity are changing in desired directions. This pinpoints topics for more detailed professional review. It is incumbent on doctors to match the concern over the efficient use of health services with information about their effects on people's health.