AIM:To investigate the utility of K-ras mutation analysis ofultrasound guided fine-needle aspirate biopsy of pancreaticmasses.METHODS:Sixty-six ultrasound guided fine-needle biopsieswere evaluated by cytology,histology and k-ras mutation.The mutation at codon 12 of the k-ras oncogene wasdetected by artificial restriction fragment lengthpolymorphisms using Bst NI approach.RESULTS:The presence of malignant cells was reported in40 of 54 pancreatic carcinomas and K-ras mutations weredetected in 45 of the 54 FNABs of pancreatic carcinomas.Thesensitivity of cytology and k-ras mutation were 74%and 83%,respectively.The speciality of cytology and k-ras mutationwere both 100 %.The sensitivity and speciality of k-ras mutationcombined with cytology were 83%and 100 %,respectively.CONCLUSION:High diagnostic accuracy with acceptablediscomfort of FNAB make it useful in diagnosis of pancreaticcarcinoma.Ultrasound guided fine-needle biopsy is a safeand feasible method for diagnosing pancreatic cancer.Pancreatic carcinoma has the highest K-ras mutation rateamong all solid tumors.The mutation rate of k-ras is about80-100 %.The usage of mutation of codon 12 of k-rasoncogene combined with cytology is a good alternative forevaluation of pancreatic masses. AIM: To investigate the utility of K-ras mutation analysis ofultrasound guided fine-needle aspirate biopsy of pancreaticmasses. METHODS: Sixty-six ultrasound guided fine-needle biopsieswere evaluated by cytology, histology and k-ras mutation. The mutation at codon 12 of the k-ras oncogene wasdetected by artificial restriction fragment length polymorphisms using Bst NI approach. RESULTS: The presence of malignant cells was reported in 40 of 54 pancreatic carcinomas and K-ras mutations were detected in 45 of the 54 FNABs of pancreatic carcinomas. the sensitivity of cytology and respectively. The sensitivity and specificity of k-ras mutation combined with cytology were 83% and 100%, respectively. CONCLUSION: High diagnostic accuracy with acceptable disability of FNAB make it useful in diagnosis of pancreaticcarcinoma. Ultrasound guided fine-needle biopsy is a safe and feasible method for diagnosing pancreatic cancer. Pa ncreatic carcinoma has the highest K-ras mutation rateamong all solid tumors. The mutation rate of k-ras is about 80-100%. The usage of mutation of codon 12 of k-rasoncogene combined with cytology is a good alternative forevaluation of pancreatic masses.