Over recent years significant molecular advances have led to a better understanding of the genetics of both syndromic and non-syndromic paediatric cancers. In addition many hereditary cancer predisposition syndromes are now recognised, some of which have implications for children in affected families. Improvements in gene mutation screening will increase the sensitivity, accuracy and therefore the applicability of genetic testing in these conditions. This review will deal with four main areas pertaining to paediatric cancer genetics (i) genetic aspects of some non-syndromic paediatric cancers (ii) paediatric cancer predisposition syndromes, (iii) the management of children in families with predominantly adult- onset cancer predisposition syndromes and (iv) special ethical, legal, social and psychological considerations in the management of children, with actual or possible genetic cancer predisposition. Current concepts and controversies in the rapidly changing field of paediatric cancer genetics will be examined in detail and the application of existing guidelines and their limitations will be discussed.