WNT signalling has a key role in early embryonic patterning through the regulation of cell fate decisions, tissue polarity and cell movements. In the nervous system, WNT signalling also regulates neuronal connectivity by controlling axon pathfinding, axon remodelling, dendrite morphogenesis and synapse formation. Studies, from invertebrates to mammals, have led to a considerable understanding of WNT signal transduction pathways. This knowledge provides a framework for the study of the mechanisms by which WNTs regulate diverse neuronal functions. Manipulation of the WNT pathways could provide new strategies for nerve regeneration and neuronal circuit modulation.