Global consumer spending trends indicated a growth in the popularity and support of green-marketing in many retailers within the formal sector with the exception of South Africa (SA). The research contained in this study therefore sets out to gain understanding of whether retailers within the formal sector of SA thought green-marketing could create a sustainable competitive advantage for them. Rigorous and methodologically sound exploratory case study research was conducted where the literature reviewed provided no answers, with the result of research questions. The design of this study was multiple unit of case analysis within an embedded design. The context was retailers within SA formal sector; the case was Massmart with two embedded units of analysis being Builders Warehouse (1) and Makro (2). The results were then used to address the primary research objective, to discover if green-marketing could be a sustainable competitive advantage for retailers within SA. Findings of this study suggested that the SA retail market would evolve towards pursuing a green-marketing strategy, firstly to achieve a short-term competitive advantage; however the competitive advantage would not be sustainable due to green-marketing becoming the norm and not the exception. Furthermore, in the long-term, retailers who do not engage in a green-marketing strategy will not be sustainable within SA.