Buyers and suppliers must concern themselves with opportunism, a phenomenon empirically established in exchange relationships. What causes firms to behave opportunistically? What are the consequences of firms' opportunistic behavior? To date, these antecedents and consequences have not been comprehensively synthesized. Herein, the opportunism phenomenon is revisited to expose research gaps and chart new directions that will enhance our understanding of buyer-supplier relationships. First, we provide a brief review of two critical theories of exchange that provide a theoretical foundation for opportunism. We next provide an overview of opportunism. Then each of the antecedents and consequences is discussed with emphasis on the contribution of each finding. Finally, and most importantly, several promising paths for further research are proposed. © 2007 Elsevier Inc. All rights reserved.