Aminoglycoside antibiotics are reported to enhance the amylase release from isolated slices of pancreas in vitro and the mode of action of aminoglycosides on amylase release is considered different from those of acetylcholine or cholecystokinin(CCK), i.e., electronmicroscopically intact zymogen granules are appeared in the lumen of pancreatic acini by treatment of aminoglycosides. It is known that atropine blocks the secretagogue effect of acetylcholine, and phenoxybenzamine is reported to block the effects of CCK or its analogue caerulein. Present study was undertaken to investigate the mode of action of aminoglycosides on the amylase release using atropine, phenoxybenzamine and propranolol as a membrane stabilizing agent in slices of chicken pancreas. The results are summarized as follows : 1) Streptomycin and kanamycin increased the amylase release significantly from slices of chicken pancreas. 2) The effect of streptomycin was inhibited by atropine but not by phenoxybenzamine or propranolol. 3) The amylase release by acetylcholine was blocked by atropine tut the effect of cholecystokinin octapeptide(CCK-8) was not influenced by atropine, phenoxybenzamine or propranolol. 4) Pretreatment of streptomycin enhanced the secretagogue effect of acetylcholine or CCK-8. From these results it is suggested that amylase releasing effects of aminoglycosides are mediated in part by cholinergic stimulation and in part by membrane alteration and these effects are enhanced by acetylcholine or cholecystokinin.