As many as 96% of all residents of Taiwan have been enrolled in the National Health Insurance (NHI) program since 1996. The NHI database was used to examine the prevalence and incidence of schizoprenia. The National Health Research Institute provided a database of 200 432 random subjects, about 1% of the population, for study. By means of exclusion criteria, a random sample of 136 045 subjects as a fixed cohort dated from 1996-2001 was obtained. Those study subjects who had at least one service claim during these years for either ambulatory or inpatient care, with a principal diagnosis of schizophrenia, were identified. The cumulative prevalence increased from 3.34 per 1000 to 6.42 per 1000 from 1996 to 2001. The annual incidence density decreased from 0.95 per 1000/year to 0.45 per 1000/year from 1997 to 2001. Male subjects had higher treated prevalence in younger age groups than did female subjects. Higher prevalence was associated with the 25-44 and 45-64 age groups, insurance amount less than US$640, the eastern region, and suburban areas. Lower incidence was associated with the 45-64 age group. Higher incidence was associated with insurance amount less than US$640, and the eastern region. According to the trends of cumulative prevalence and incidence density, the treated prevalence and incidence rate will be approximate to community rates gradually. Most persons with schizophrenia had received treatment in Taiwan after the NHI program was implemented. Future studies should focus on outcome and cost evaluation.