This paper describes a statistical study within NHS health districts, using routinely available data, of the supply of outpatient services, the demands made on these services and the resulting balance of supply and demand. Indicators of supply have been investigated which aim to reflect the resources available within a district for outpatient services and indicators of demand have been studied which link to the number of general practitioners who are considered likely to make use of the services provided. Some preliminary analysis is attempted of relationships between the observed balance of supply and demand and the predictions based on the statistical models developed.