This article describes the reciprocal interactions between neurones and Schwann cells with particular reference to the role of growth factors and neurokines as signalling molecules between these cells and of the extracellular matrix as a conduit for such signalling. Major recent advances have identified molecules produced by neurones that are responsible for Schwann cell proliferation, as well as some of the Schwann cell factors regulating the expression of molecules shown to play an important role in neuronal survival and differentiation.