This text is aimed at those involved with cancer research, particularly those interested in epithelial cancers of the aerodigestive tract accounting for one third of all cancer deaths each year. The recent discovery of two groups of genes, oncogenes and tumour suppresor genes has thrown doubt on the possibility of a genetic predisposition in all cases. The current knowledge and recent results concerning the role of tumour suppressor genes in oral carcinogenesis are described, as is the importance of understanding the basic principles and the application of molecular biology techniques.