The community periodontal index of treatment needs (CPITN) has been recommended for epidemiological surveys of periodontal status and treatment needs. The prevalence of gingivitis, periodontitis and missing teeth in a study population has been determined using the CPITN and GPM/T (gingivitis: periodontitis: missing teeth) indices. In this study, a survey of periodontal disease was performed among the adult population of Taipei City using the CPITN index. A total of 673 dentated persons (male 339, 50.4%; female 334, 49.6%) were examined and surveyed. Data were then divided into five age groups, 15-19, 20-29, 30-44, 45-64 and 64+. The prevalence of periodontal disease was analyzed using the percentage or sextant from all teeth. Treatment needs were determined by the worst periodontal score per sextant. It was found that about 91% of subjects suffered from various degrees of periodontal disease in at least one tooth. Gingivitis and periodontitis were 86.9% and 33%, respectively. Among them 48.9% had missing teeth. The prevalence of periodontitis and missing teeth increased with age. Most of them involved oral hygiene instruction and scaling. About 11.0% of the subjects needed periodontal surgery. Higher proportions of attachment loss with gingival recession caused by destructive periodontal disease were found in older persons who did not require periodontal surgery. It was concluded that endemic gingivitis and calculus, a moderate prevalence of shallow pockets and a low prevalence of deep pockets were observed among adults in this group in Taipei City and that the CPITN is a practical epidemiological and public health method for screening the periodontal status and treatment needs of a population.