Germline specific point mutations in the gene encoding fibroblast growth factor receptor 3 (FGFR3) are associated with autosomal dominant human skeletal dysplasia and craniosynostosis syndromes. Mutations identical to the germinal activating mutations found in severe skeletal dysplasias have been identified in certain types of cancer: at low frequency in multiple myeloma and cervix carcinoma and at high frequency in bladder carcinoma. We analysed, by SSCP and sequencing, the prevalence of FGFR3 mutations in 116 primary tumours of various types (upper aerodigestive tract, oesophagus, stomach, lung and skin). The regions analysed encompassed all FGFR3 point mutations previously described in severe skeletal dysplasia and cancers. No mutations were detected in the tumour types examined, suggesting that FGFR3 mutations are restricted to a few tumour types, the evidence to date suggesting that they are very specific to bladder carcinomas.