The paper by McCormick et al. (2010) provides real-world examples of best practice for implementing alcohol screening and brief intervention (SBI) in primary care. We commend the authors for that and also wish to highlight the additional challenges involved in implementing SBI in primary care among vulnerable populations, especially problem drug users. To explore the scientific evidence on implementing best practice in SBI for problem alcohol use among problem drug users, we conducted a Medline search with the following keywords: setting (primary care),target behaviour (problem alcohol use), population (problem drug users) and implementation strategies (e.g. guidelines, barriers or enablers). The majority of papers we identified concerned the general adult population and we consider this literature in conjunction with that specific to problem drug users, where relevant.