Pancreatic carcinomas have a high incidence of Ki-ras mutations, and the genetic change is thought to occur at an early stage in the carcinogenesis. The aim of this study was to evaluate the usefulness of detecting genetic mutations in pure pancreatic juice (PPJ). DNA was extracted from tissue specimens of pancreatic carcinomas and from cells in PPJ, and subjected to polymerase chain reaction-single-strand conformation polymorphism analysis. Two types of mobility shifts that indicate Ki-ras mutations were observed in 13 of the 20 (65%) tissue specimens obtained by operation or autopsy. Ten of 15 specimens (67%) of PPJ collected from patients with pancreatic carcinomas showed two types of mobility shifts. Conventional imaging techniques did not show two in 10 of these patients. PPJ from patients with non-cancerous pancreatic diseases showed no Ki-ras mutations. The p53 tumor suppressor gene, examined by PCR-SSCP analysis, was mutated in 8 of the 20 tissue specimens obtained by operation or autopsy (40%). The detection of Ki-ras and p53 mutations in PPJ could be useful for the early diagnosis of pancreatic carcinomas, especially for neoplastic lesions of the intraductal type.