Mutations in the p53 tumour suppressor gene are common in a wide range of human malignancies. In particular G-T transversions in the p53 gene occur at a high frequency in lung cancer tumours and as the same mutagens maybe responsible for p53 mutations in head and neck squamous cell carcinomas, a preliminary investigation was carried out to establish if this may be the case. Codon 249 of the p53 gene has been found to be a hot spot of G-T transversions in hepatocellular carcinomas, thus it was decided to initially investigate this site using specific primers and restricting the PCR product with the HaeIII restriction endonuclease. Fifty seven squamous cell carcinomas of the head and neck were investigated using this technique and no mutations were found at codon 249 in the p53 gene. In this study twenty six of the specimens were also examined immunohistochemically using a number of antibodies to p53 (PAb 421, PAb 1801 and CM-1), and 19 were found to have positive staining. Moreover as positive p53 staining is considered to be synonymous with p53 mutations, over two thirds of our earlier immunohistochemical study indicated p53 mutations in head and neck tumours. The technique used in this paper has the advantage of scanning a large number of tumours for mutations at suspect sites and maybe of use in the future if specific mutational hot spots are found in the p53 gene in head and neck cancers. In the meantime p53 mutations in these tumours are been investigated by conventional sequencing techniques.

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