Two hundred and seventy dentists, systematically selected from the membership lists of the Hong Kong Dental Association, were sent forms on which they were invited to record the reasons for tooth extraction in all patients aged 16 years and above over a period of five to six weeks. Third molars were excluded. Fifty-five per cent of the recording sheets dispatched were returned with usable data. Data were provided on 8516 extractions performed for 6331 patients. Overall caries was the reason given for 60 per cent of extractions; periodontal disease for 28 per cent; prosthetic indications for six per cent; trauma (which included tooth wear) for four per cent; and orthodontic and other reasons for two per cent. Extractions for periodontal reasons were more common in those aged 40 years and above, but periodontal disease did not exceed caries as a reason for extraction even in those aged 60 years and over. The tooth type most frequently extracted was the first molar. Mandibular incisors were the teeth most commonly extracted for periodontal reasons. In this community, which has benefited from water fluoridation since 1961, caries was the dominant reason given by dentists for tooth extractions in all age groups of the subjects studied.