Purpose: The aim of this paper is to review research on knowledge management in small and medium-sized enterprises to identify gaps in the current body of knowledge, which justify future research directions. Design/methodology/approach: The study consists of a systematic review of 36-refereed empirical articles on knowledge management and small and medium-sized enterprises. Findings: The areas of knowledge management implementation, knowledge management perception, and knowledge transfer are relatively well researched topics; whereas those of knowledge identification, knowledge storage/retention and knowledge utilisation are poorly understood. Given the prevalence of small and medium-sized enterprises there is a strong need for more research on this important topic. The future research directions proposed by the authors may help to develop a greater understanding of knowledge management in small and medium-sized enterprises. Research limitations/implications: By only using the ProQuest database this study may not have allowed a complete coverage of all empirical articles in the field of knowledge management in small and medium-sized enterprises. Yet, it is believed that the findings provide a valuable understanding of the current situation in this research field. The study proposes a number of future research directions, which may stimulate more intensive research in this important field. Originality/value: To the best of the authors' knowledge, no systematic literature review on this topic has previously been published in academic journals. © Emerald Group Publishing Limited.