Derivatives of 3-(β-aminoethyl)-1,2,4-triazole similar to histamine have been resynthesized and studied. Four well-known effects of histamine have been considered (the contractions of an isolated guinea pig terminal ileum, dog gastric acid secretion, contractile frequency of an isolated guinea pig right atrium, blood pressure lowering effect in cats). Newly synthesized compounds IEM-813 and IEM-759 exerted some selective effect on H1-and H2-receptors: IEM-813 showed greater affinity for gut-isolated H1-receptors than for stomach and atrium H2-receρtors, while IEM-759 mainly influenced H2-receptors. Accordingly, the influence of 1,2,4-triazole analogues on H1- and H2-receptors is subject to structural demand