The type 1 insulin-like growth factor receptor (IGF-1R) plays an essential role in mammalian growth and development, and has emerged as a candidate therapeutic target in the treatment of cancer. While the pleiotropic cellular responses elicited following tyrosine phosphorylation of the IGF-1R is usually seen to involve the direct recruitment/activation of classical intracellular effector proteins, it is now clear that cross-talk between the IGF-1R and members of distinct receptor families also plays a significant role in effecting intracellular signalling. In recent years, a number of studies have highlighted the interaction(s) between the IGF-1R and the epidermal growth factor receptor (EGFR), another transmembrane tyrosine kinase that is an established cancer target. This review describes the components of the IGF signalling system and gives an overview of the emerging picture of the interrelationship that is now known to exist between the IGF and EGF receptors.