OBJECTIVES: For many courses of therapy, assessments of treatment effectiveness are used to inform treatment continuation decisions.  If a “mid-therapy” assessment (MTA) is positive, the patient is indicated to continue treatment; if negative, treatment may be discontinued.  Using expected utility theory, we demonstrated previously that the availability and timing of such assessments may influence patients’ treatment initiation decisions.  We conducted a pilot study among chronic hepatitis C (CHC) patients to examine preferences over MTA timing and treatment initiation. METHODS: A stated preference survey was developed and pre-tested among 10 community volunteers and then administered to 49 CHC patients.  The survey described two MTAs for CHC treatment:  one at 4 weeks (rapid virologic response, RVR) and the other at 12 weeks (early virologic response, EVR).   Test characteristics varied between the two MTAs, but the decision algorithm (stated above) was held constant.   Multiple response formats were used  to elicit preferences across MTA and treatment initiation.  Results are summarized as means and proportions.  RESULTS: Average age was 54.6 yrs; 55.1% were male; 32.7% were treatment-naïve; 67.3% reported their general health as good or better.  Three subjects failed to answer one or more MTA or treatment choice questions.  More subjects had previously heard of EVR compared to RVR (43.8% vs. 14.3%, p>0.01).  Given a choice between MTAs, 55.3% of subjects indicated a preference for RVR.  Treatment utilizing RVR was somewhat or strongly preferred by 57.4% of subjects, and 61.2% said they would choose RVR if only one test was available.  However, more subjects responded that they would accept treatment with EVR than with RVR 60.9% vs. 55.3% (difference not significant).   CONCLUSIONS: Patients with CHC consistently indicated MTA preferences that are at odds with current treatment guidelines.  Further research is needed to understand the relationship between MTA preference and treatment initiation.