Ten thousand self-referred Sydney inhabitants were screened for major coronary risk factors over one year. Individual "problems" were referred to general practitioners for further assessment and treatment. Seventy-four per cent of subjects have attended a general practitioner where relevant. For subjects under 65 years, 29% had unsuspected hyperlipidaemia, 11% had unsuspected hypertension, and 0.6% had unsuspected diabetes. Nineteen per cent of subjects reported a past history of hypertension, of whom 46% appeared to be well-controlled (diastolic blood pressure less than 95 mmHg). The numbers of cigarette smokers fell with increasing age. Considering hyperlipidaemia, hypertension and cigarette smoking in subjects under 40 years of age, 10.4% of males and 4.9% of females had two or more coronary risk factors. Three hundred and fifty-four subjects selected at random, who claimed to be receiving treatment as a result of initial screening were invited for retesting eight and 15 months later. Significant falls were noted in body weight, blood pressure, and plasma cholesterol readings.