OBJECTIVES: With 10% of the population infected by hepatitis B virus (HBV), hepatitis B is the top infectious disease in China. It is estimated that pharmaceutical cost accounts for about 60% of the medical cost for CHB. This study aims to analyze the possible differences in the amount and composition of the pharmaceutical cost between insured and uninsured CHB inpatients. METHODS: We examined 549 inpatient medical records of CHB from hospitals in Beijing, Harbin and Mudanjiang. The time spans from 1999 to 2002. We studied following variables: general information, health insurance status, occupation, state of illness (symptom, physical sign, and complication), usage of pharmaceuticals, prices of pharmaceuticals, etc. The samples were divided into two groups according to different disease states: compensated cirrhosis group and decompensated cirrhosis group. RESULTS: Pharmaceutical cost accounts for 68% of the total inpatient cost. In the comp. cirr. group, the pharmaceutical cost per insured patient is 87% higher than that of noninsured patient, while in the decomp. cirr. group, pharmaceutical cost per insured patient is twice as high as that of noninsured patient. The average hospital stay is 37 days in insured compared with 23 days in noninsured. There is no difference in average daily pharmaceutical cost between the insured and noninsured in the comp. cirr. Group, while in the decomp. cirr. group, the daily pharmaceutical cost of insured is 31% higher than that of noninsured. The frequency of using high-cost medicines in the insured is also significantly higher than that in the noninsured. CONCLUSIONS: Health insurance coverage does have influences on the costs of pharmaceuticals among CHB inpatients. The influences lie in the following three aspects: extending hospital duration, increasing daily cost and enhancing the frequency of using high cost medicines.