The therapeutic effectiveness of a conventional (Pankreon-Granulat) and an acid-protected (Kreon) porcine pancreatic enzyme preparation, and an acid-stable fungal enzyme preparation (Nortase) in the treatment of severe pancreatogenic steatorrhoea was investigated. The study comprised 17 patients with chronic pancreatitis and exocrine pancreatic insufficiency with (A) or without (B) a previous Whipple's procedure (B II resection + partial duodenopancreatectomy). With all three enzyme preparations, a significant (p less than 0.05) reduction in the total faecal fat excretion/day was achieved. In therapy group A, this reduction was, on average, 58% for Kreon (100,000 U lipase/day), 67% for Pankreon-Granulat (360,000 U lipase/day) and 54% for Nortase (75,000 U lipase/day), the respective figures for therapy group B being 58%, 52% and 46% at identical dosages. Thus, in both groups, the effect produced by the conventional porcine pancreatic enzyme preparation and the acid-protected porcine or the acid-stable fungal enzyme preparation was largely equivalent, although the latter two preparations were administered at only 1/4 of the dosages of the former preparation. On the basis of the respective average reduction in total faecal fat excretion and average number of stools/day, it would appear that in patients with chronic pancreatitis and prior Whipple's procedure, Pankreon-Granulat should be administered for enzyme replacement while in patients with an intact upper gastrointestinal tract, Kreon should be administered, in the treatment of steatorrhoea in chronic pancreatitis.