Business service sourcing is increasing in importance for firms; a trend recognised by significant research efforts among scholars. The rapidly expanding literature is, however, highly fragmented. It is difficult to grasp what has actually been investigated, and what remains to be studied. Therefore, the purpose of this article is to review, analyse and categorise empirical research in the area of business service sourcing. A total of 119 empirically-based articles published in peer-reviewed journals were identified and classified according to their focus of research, empirical context, and research methodology. Most articles dealt with the sourcing process or sourcing strategy, less with antecedents to sourcing and sourcing outcomes. Logistics and information systems/information technology services have received the most attention, as have European and North American service buyers. A majority of articles employed statistical methods of analysis.