This project was concerned with the clinical knowledge reported by general practitioners in relation to the diagnosis and management of seven common clinical conditions: acute otitis media, jaundice, iron-deficiency anaemia, transient cerebral vascular insufficiency, infectious mononucleosis, pulmonary infarction, and carcinoma of the prostate. Postal questionnaires were sent to three groups of doctors: a constant group of experienced general practitioners who were or had been trainers, randomly selected groups of 200 general practitioners, and small groups of consultants who were specialists in each condition. The last two groups were changed for each of the chosen clinical conditions; the constant group remained the same throughout. The study was not concerned with the attitudes and skills of general practitioners or consultants, and no attempt has been made to analyse the process of clinical problem-solving. The differences between the constant group and random group of general practitioners were minor. Consultants received questionnaires identical to those sent to general practitioners and were asked to answer them as they would expect a competent general practitioner to do; their answers suggested a more direct approach to the problem concerned than those given by general practitioners. The information obtained has implications for education for general practice and educational audit programmes. Areas for further research are suggested.