The synthesis and gastric antisecretory activity of a series of indole-1-alkanamides and pyrrole-1-alkanamides are presented. A marked elevation of the pH of the gastric secretions of the rat was observed after oral administration of 100 mg/kg of 2,3-dimethylindole-1-acetamide (2), -1-propionamide (8), and -1-butyramide (13). Replacement of either methyl group by a hydrogen atom or an ethyl radical resulted in greatly diminished activity. In the acetamide and propionamide series the 3-hydroxymethyl-2-methyl (14 and 15) derivatives exhibited activity but only when administered by the subcutaneous route. 2,3-Dimethylindole (18) was active and 2,3,4,5-tetramethylpyrrole-1-acetamide was moderately active. A number of the activ compounds were tested in the mouse mydriasis test for anticholinergic activity and found to be inactive. They were also found to be inactive in blocking histamine-induced acid secretion in the dog.