© Springer Science+Business Media, LLC, part of Springer Nature 2018. In an HIV-hepatitis B virus (HIV-HBV) coinfection cohort in Zambia, we piloted a qualitative point-of-care (POC) test for urine Ethyl glucuronide (uEtG), assessed concordance between uEtG and alcohol use disorders identification testconsumption (AUDIT-C), and identified epidemiological factors associated with underreporting (defined as uEtG-positivity with last reported drink > 7 days prior). Among 211 participants (40.8% women), there were 44 (20.8%) lifetime abstainers, 32 (15.2%) former drinkers, and 135 (64.0%) current drinkers, including 106 (50.2%) with unhealthy drinking per AUDITC. Eighty-seven (41.2%) were uEtG-positive including 64 of 65 (98.5%) who drank ≤ 3 days prior and 17 of 134 (12.7%) underreported, all of whom admitted to recent drinking when results were discussed. uEtG was moderately concordant with AUDIT-C. Past drinking (versus lifetime abstinence) and longer time on antiretrovirals (≥ 12 months) were associated with underreporting. These data support further use of POC alcohol biomarkers in HIV and hepatitis research and clinical settings.