OBJECTIVES: This study aims to investigate the follow up and utilization of drug treatment for chronic HBV/HCV patients with major psychiatric diseases in Taiwan.  METHODS: Data sources came from a 6-year population-based dataset of Taiwan National Health Insurance claims data files during 2007-2012 on patients with schizophrenia, bipolar disorder, and delusional disorder, among them HBV/HCV cases were identified if at least 2 outpatient visits with ICD-9-CM code = 070.32 for HBV and ICD-9-CM code = 070.54 for HCV in any given year had been sought. A comparison cohort from non-psychiatric population was established by matching the psychiatric HBV/HCV cases at a 1: 4 (cases: comparisons) ratio on the basis of age, gender, and urbanization level of the index hospital. Differences in follow-up examination and treatment intensity within one year after the index date between the cases and comparisons were assess by Chi-square tests and t-tests, as well as generalized linear model regressions. All analyses were stratified by type of psychiatric diseases and HBV/HCV. RESULTS: For HBC patients with schizophrenia, a significant lower follow-up rate on the abdominal ultrasound (0.67 vs. 0.78, p<0.0001), alpha-fetoprotein (0.70 vs. 0.78, p<0.0001), GOT (0.76 vs. 0.84, p<0.0001), and GPT examinations (0.80 vs. 0.88, p<0.0001), and significant lower utilization of drug treatments was also found (12.72 vs. 20.83, p<0.0001). Lower follow-up and utilization of drug treatment were found among HBV/HCV patients with other types of psychiatric diseases. CONCLUSIONS: Awareness of comorbidity with viral hepatitis in psychiatric patient groups should be enhanced and appropriate treatment should be evaluated thoroughly.