In a double-blind study on 19 patients with the diagnosis of chronic pancreatitis, the effects of treatment with a granulated pancreatic enzyme preparation (Pankreon) were compared with those of placebo administration. One week of treatment with each preparation was preceded by one week without any medication. The patients kept daily records of their symptoms, plotting the severity of pain on an analog scale. Weekly assessments of the mean pain level were also made by an examiner questioning the patients. Recordings of body weights and pancreas and liver laboratory tests were done weekly. Fifteen of 19 patients noted less pain during the week of treatment with pancreatic enzymes as compared to that of placebo treatment (P less than 0.05). The average reduction of pain, as calculated for all patients, was 30% as evaluated by both patients (P less than 0.01) and the examiner (P less than 0.05). No differences were found in other parameters examined. A possible explanation of the findings could be an effect on the intraductal pressure by intraluminal trypsin.