The objective of this study was to assess the prevalence of barriers to interferon treatment in a population of HIV/HCV coinfected patients. A cross-sectional study was conducted at two AIDS Outpatient Clinics in Brazil. The study included all HIV infected patients followed at these institutions from January 2005 to November 2007. Medical records of 2,024 HIV-infected patients were evaluated. The prevalence of anti-HCV positive patients among them was 16.7%. Medical records of HCV/HIV coinfected patients were analyzed. 189 patients with the following characteristics were included in our study: mean age 43 years; male gender 65%; former IDUs (52%); HCV genotype 1 (66.4%); HCV genotype 3 (30.5%); median CD4+ T cell count was 340 cells/mm3. Among 189 patients included in the analyses, only 75 (39.6%) were considered eligible for HCV treatment. The most frequent reasons for non-treatment were: non-compliance during clinical follow-up (31.4%), advanced HIV disease (21.9%), excessive alcohol consumption or active drug use (18.7%), and psychiatric disorders (10.1%). Conclusions: In Brazil, as in elsewhere, more than half of HIV/HCV coinfected patients (60.4%) have been considered not candidates to received anti-HCV treatment. The main reasons may be deemed questionable: non-adherence, drug abuse, and psychiatric disease. Our results highlight the importance of multidisciplinary teams to optimize the access of coinfected patients to HCV treatment.