Acute nociceptive pain is a key defence system that enables the detection of danger signals that threaten homeostasis and survival. However, chronic pain (such as the neuropathic pain that occurs after peripheral nerve injury) is not simply a consequence of the continuity of acute nociceptive signals but rather of maladaptive nervous system function. Over recent decades, studies have provided evidence for the necessity and sufficiency of microglia for the alterations in synaptic remodelling, connectivity and network function that underlie chronic pain and have shed light on the underlying molecular and cellular mechanisms. It is also becoming clear that microglia have active roles in brain regions important for the emotional and memory-related aspects of chronic pain. Recent advances in the development of new drugs targeting microglia and the establishment of new sources of human microglia-like cells may facilitate translation of these findings from bench to bedside.