Despite the growing body of literature on sales and operation planning (S&OP), efforts to synthesise the overall state of the art of research in this area are limited. Within this context, this paper provides a systematic review of the literature on S&OP. The purpose of this systematic review is twofold: (i) to integrate the highly dispersed work on S&OP in order to identify and analyse S&OP as a business process and (ii) to assemble quantitative evidence of its impact on the performance of the firm. A literature search framework is proposed, with 271 papers reviewed and classified. The framework embraces S&OP context information, inputs and goals, structure and processes, outcomes, and results. The major expected outcome in most papers was a cross-functional integration of plans, although few studies report on the integration of finance plans into S&OP. Despite the existence of common process descriptors and definitions of S&OP, there is a lack of unifying frameworks for maturity models, measurement of S&OP, and constructs related to the firm's performance. The need for additional scientifically sound survey or case study research on S&OP is emphasised. This paper contributes to a better understanding of S&OP's role as a determinant of firm's performance in the supply chain.