Approximately 2.7 million Americans have active Hepatitis C infection. Combination therapy with ribavirin and interferon alfa-2b has emerged as the treatment of choice for Hepatitis C. OBJECTIVES: To determine if the prescribing of combination therapy differed among ethnic groups in Hepatitis C-infected members during calendar year 1999 in a Medicaid MCO. METHODS: Hepatitis C-infected patients were identified from a database of continuously enrolled members of an inner-city Medicaid MCO in Philadelphia using ICD-9 codes indicative of Hepatitis C (070.41, 070.44, 070.51, 070.54, 571.40, 571.41, V02.60, V02.62). From this population, members who received combination therapy with ribavirin and interferon alfa-2b were identified and demographic information was obtained. Variation in the prescribing of combination therapy among ethnic groups was assessed using a Chi-square test. RESULTS: From a cohort of 73,869 members, 395 members (0.535%) had an ICD-9 code for Hepatitis C. Of those, 60 members had pharmacy claims for combination therapy during 1999. These members aged from 23 to 64 years (mean age=45.0 yrs; SD=7.6). Based on the ethnic distribution of the 395 members with an ICD-9 code for Hepatitis C, 8.4% (16/191) of African-Americans were prescribed combination therapy compared with 23% (28/122) of Caucasians, 22.7% (15/66) of Latinos and 14.3% (1/7) of Asian-Americans. A statistically significant difference in the prescribing of combination therapy was noted among ethnic groups (p<0.05). CONCLUSIONS: Within this Medicaid MCO, a disproportionately low percentage of African–American members received combination therapy for Hepatitis C during 1999. It is unknown whether this was due to a disproportionate number of contraindications in this group, inequitable prescribing habits of physicians, cultural barriers preventing consent for treatment, or noncompliance with obtaining the medication. Further investigation is needed to determine why this disparity exists so that differences in treatment among ethnic groups may be minimized.