Fractional flow reserve (FFR) is a useful tool for the evaluation of coronary bifurcation lesions. FFR can guide treatment strategy, simplify the procedure and reduce unnecessary complex interventions. However, the application of FFR to complex bifurcation lesions requires a comprehensive understanding of its roles and potential pitfalls. Furthermore, FFR should be interpreted in the context of complex bifurcation anatomy and physiology rather than as a simple number. Finally, it should be recalled that the ischaemic burden is more important than the presence of ischaemia, and the risk/benefit of a complex intervention should be incorporated into the treatment decision after FFR measurement.