摘要 Abstract : BACKGROUND: The purpose of the study is to investigate the epidemiology of Creutzfeldt-Jakob disease (CJD) and multiple sclerosis (MS) in Taiwan. METHODS: Cases of CJD and MS were identified from the National Health Insurance Research Database from January 2000 to December 2005. Age- and sex-specific incidences of these diseases were estimated by dividing the incidence number by population data obtained from the Department of Statistics, Ministry of the Interior. RESULTS: During the study period, 79 cases of CJD, 41 women and 38 men, were identified. The average annual incidence rate was 0.63/million. Most cases were older than 60 years. There were 1,262 cases of MS. The male-to-female ratio was 0.4. The average annual incidence rate was 0.79/100,000. The incidence reached a peak at the age group of 40-60 years for females and at the age group of over 55 years for males. The prevalence of MS was 2.96/100,000 in 2005, which is higher than those of previous studies in Taiwan. CONCLUSIONS: The annual incidence rate of CJD in Taiwan is lower than in western countries. The annual incidence rate and prevalence of MS in Taiwan are low. The prevalence of MS in Taiwan increased in recent decades.