Seven double-pouch dogs with one vagally innervated Amdrup pouch (AP) and one denervated and denervated mucosa at the same time in the same animal. Stimulation was done by food, a mixture of liver, heart and bonemeal, 10 g/kg. Cimetidine, 25, 50, 100, 200, and 400 mg; atropine, 0.031, 0.125, 0.5 and 1.0 mg; somatostatin, 0.5, 1.0, and 2.0 micrograms/kg/h; and secretin 2 U/kg/h, were given 60 min after the meal, one single dose on each day. Atropine and somatostatin lowered pepsin secretion in both pouches, significantly more in denervated mucosa for all doses of somatostatin and for the lower doses of atropine. Higher doses of atropine nearly abolished the secretion in both pouches. Cimetidine lowered pepsin output only in denervated mucosa. In innervated mucosa the output was unchanged or significantly increased (50 mg) by cimetidine. Secretin increased pepsin output significantly in both pouches, more in innervated mucosa. When the infusion of somatostatin was topped, a marked rebound effect was seen in the innervated pouch.