We have reported the presence of c-K-ras oncogenes activated by single point mutations at codon 12 in a vast majority of human pancreatic carcinomas. Formalin-fixed, paraffin-embedded specimens from surgical resections, autopsies and biopsies were used as well as snap frozen surgical specimens. The high oncogene incidence has been confirmed in other studies and indicate that somatic mutational activation of the c-K-ras gene is an important event in the development, maintenance or progression of cancer of the exocrine pancreas. While the role that these point mutations play in any or all of these processes remains to be determined, their presence is useful clinically for the diagnosis of pancreatic carcinoma at the molecular genetic level. The detection of mutated c-K-ras oncogenes in fine needle aspirates of pancreatic masses, that by cytomorphology may be suspicious but not diagnostic of malignant disease, increases the sensitivity of the diagnosis for this cancer. The identification of codon 12 mutations in the c-K-ras gene in pancreatic adenocarcinomas has been possible by advances in recombinant DNA techniques, especially by the development of in vitro gene amplification by the polymerase chain reaction (PCR). The possibility of analysing formalin-fixed, paraffin-embedded tissue for the presence of genetic alterations as small as single point mutations by PCR in concert with other mutation detection techniques, should facilitate the molecular genetic analysis of pancreatic carcinoma. Retrospective studies using stored specimens are now feasible with the technology described and should yield important information on the molecular epidemiology and aetiology of this and other diseases.