Hereditary pancreatitis is a rare form of pancreatitis, accounting for approximately 1% of all types of pancreatitis. It is inherited as an autosomal dominant disease, with incomplete penetrance. The genetic defect is believed to be caused by mutations in the trypsinogen gene. Patients who inherit the disorder suffer from a form of pancreatitis that resembles other types of pancreatitis, but the age of onset is much earlier. Sixteen biopsy-proven pancreatic cancers have developed in a cohort of 412 patients with a median follow-up period of 18 years (interquartile range, 7 to 30 years) since the onset of symptoms. Compared with the background population, the risk of pancreatic cancer is approximately 50 to 60 times greater than expected. Smoking appears to be an additional risk factor in these patients: Smoking increases the risk of developing pancreatic cancer and lowers the age of onset by approximately 20 years. Patients with hereditary pancreatitis are urged to avoid smoking because it greatly increases the risk of pancreatic cancer and to avoid alcohol, a known risk factor for all forms of pancreatitis.