For a variety of purposes it is increasingly necessary to establish the health needs of local populations. Following a critique of existing proxies of need, this paper presents and evaluates an alternative which draws upon epidemiological evidence concerning the age, sex and social class distribution of morbidity in order to estimate the prevalence of specific conditions in designated populations. By way of demonstrating the insights to be gained through the use of these indicative prevalence rates, the paper considers the treatment of ischaemic heart disease in a sample of 539 practices and presents evidence regarding the significance of deprivation and rurality in determining health service use relative to needs.