Since 1986, annual screening for oral cancer and precancer by postal invitation has been undertaken among 60-year-old residents of Tokoname city, Japan. Clinical examination of the oral soft tissues is performed by groups of four different, specially trained general dental practitioners in the city health centre on one day each year. Following screening each subject receives an individual consultation with an oral medicine specialist. Individuals considered to need full diagnostic follow up or treatment are advised to attend a secondary care referral facility. Between 1986 and 1993, 802 out of 5187 eligible residents (15.5 per cent) were screened of whom 38 (4.7 per cent) were designated by the screeners as positive for oral cancer, erythroplakia, leukoplakia, lichen planus or chronic candidosis. Of these, 32 were referred and 25 attended for follow up examination in hospital departments by specialists with full diagnostic back up facilities. Twenty subjects were confirmed as having a potentially malignant lesion. For these referred patients only, the proportion of correct decisions by the screeners out of all oral cancer/precancer screening decisions was 81 per cent. Positive and negative predictive values for those attending for follow up were 0.80 and 0.82 respectively. Ways of improving the effectiveness and adequacy of the programme are considered.