Recurrent abdominal pain and recurrent pancreatitis are common problems associated with some patients with cystic fibrosis (CF). There is no known effective method to prevent recurrent abdominal pain and recurrent pancreatitis in such patients. The objective of this study was to determine whether nocturnal hydration (NH) prevents recurrent abdominal pain and recurrent acute pancreatitis in patients with adult-onset CF. Adult CF patients who were referred to our Pancreatic Diseases Clinic for recurrent abdominal pain and pancreatitis were enrolled in the study. Each patient was encouraged to drink plenty of water during the night and established a 6-month diary (3 months before and 3 months after NH was initiated), recording the frequency and severity of their abdominal pain, the amount of pain medication taken, and the volume of their water intake. We also reviewed the number of doctor's clinic visits, emergency room visits, and hospitalizations for about 1 year before and 1 year after the initiation of the NH. The frequency and the severity of abdominal pain in this group of patients were significantly reduced. The amount of pain medication and the number of emergency room visits and hospitalizations for abdominal pain and acute pancreatitis were reduced. NH is a simple and cost-effective method to prevent recurrent abdominal pain and pancreatitis in patients with adult-onset CF.