Hereditary pancreatitis is a rare, autosomal dominant, inherited disease characterized by recurrent attacks of acute pancreatitis with the development of chronic pancreatitis and an increased risk of pancreatic cancer. R122H or N29I mutation in cationic trypsinogen (protease serine 1, PRSS1) gene causes hereditary pancreatitis. R122H mutation is the most common mutation that causes pancreatitis by preventing deactivation of trypsin within the pancreas and prolonging its action. Three members of the family, the patient, her elder son, and her niece experienced recurrent attacks of pancreatitis. We analyzed five exons of the PRSS1 gene in DNA samples of five family members including her husband and younger son who were asymptomatic. We found out that four members of the family, the patient, her two sons, and her niece, had R122H mutation in the exon 3 of PRSS1 gene. Finally, we diagnosed hereditary pancreatitis in two households in the same family.