Deploying knowledge brokers to bridge the ‘gap’ between researchers and practitioners continues to be seen as an unquestionable enabler of evidence-based practice and is often endorsed uncritically. We explore the ‘dark side’ of knowledge brokering, reflecting on its inherent challenges which we categorise as: (1) tensions between different aspects of brokering; (2) tensions between different types and sources of knowledge; and (3) tensions resulting from the ‘in-between’ position of brokers. As a result of these tensions, individual brokers may struggle to maintain their fragile and ambiguous intermediary position, and some of the knowledge may be lost in the ‘in-between world’, whereby research evidence is transferred to research users without being mobilised in their day-to-day practice. To be effective, brokering requires an amalgamation of several types of knowledge and a multidimensional skill set that needs to be sustained over time. If we want to maximise the impact of research on policy and practice, we should move from deploying individual ‘brokers’ to embracing the collective process of ‘brokering’ supported at the organisational and policy levels.