The accepted decompression methods of chronic pancreatitis are the longitudinal pancreaticogastrostomy and the conventional pancreaticojejunostomy. The aim of the present study was to estimate the effect of these types of drainage operations on gastric acidity and to evaluate the clinical results. Between Jan. 1992 to 1996 56 patients with chronic pancreatitis were selected into the investigation who were operated in our clinic. A 24 hour gastric monitoring was taken on every patient before and 6 weeks after the operation. Following a complete postoperative check up we found that both types of operations are effective for pain relief (71%). Retrospectively 83% of the patients had no digestive problems due to pancreatic enzyme substitution. According to our statistical evaluation of 24 hour gastric pH monitoring test no alteration was detected in gastric pH in both groups pre- and postoperatively. On the basis of pH measuring and evaluated data we consider that pancreaticogastrostomy is a good operation choice to relieve intractable pain in selected patients with chronic pancreatitis associated with duct dilatation.