A systematic ophthalmological, medical, and biochemical screening of a rural population of diabetics in Western Australia is being carried out. A team of ophthalmologists, physicians, and paramedical personnel establish regional screening centres on a voluntary basis at weekends. Every attempt is made to locate and examine all known diabetics. All patients are given a thorough ophthalmic examination including standard multiple field colour fundus photography. Thorough physical examination includes assessment of cardiovascular and neurological status. Biochemical parameters include random blood sugar, urine analysis, serum creatinine, glycosylated haemoglobin, cholesterol, and high density lipoprotein. A detailed questionnaire and interview is carried out to assess the historical degree of control and the patient's knowledge of the control and management of diabetes. The sample now comprises an unselected population of 400 diabetics living in rural areas and allows comparison of areas which have scarce medical services with centres that are well supplied with medical practitioners. Incidence of retinopathy varies from 25 to 36 per cent of the diabetic population. Positive correlations of retinopathy have been found with duration, age, hypertension, level of control assessed biochemically at the time of examination, presence of ischaemic heart disease, peripheral neuropathy, and renal disease. Smoking also correlates positively. The data provide a baseline by which attempts to alter diabetic knowledge, management, and control may be measured in follow-up studies.