This paper contributes to the overall discussion on the relational resources then, in particular, attempts to recognize inter-firm investments in the agrifood industry. It is essentially grounded in an integrative approach which combines relational and resource-based views. Our goal in this paper is to find out if and how relational investment contributes to a sustainable relational advantage of business relationships in the agrifood industry. Producers, processors and traders who undertake investments in conjunction with their contractors were queried. The main areas of these investment activities and the potential of a sustainable relational advantage are explored. On this basis, a model of resource-based sustainable relational advantage in agrifood business relationships was executed. It was found that relational investments aimed at optimization of supply and provision as well as food safety and social responsibility create and sustain a relational advantage. Those aimed at technology and ecology implicate an unexploited relational advantage. Subsequent human, financial and real capital investments implicate a temporary relational advantage. The added value of this study lies in the implementation of an integrative approach to investigating the development potential of sustainable resource ties in the agrifood industry.