The solvent-free reaction of 1,2,4-triazine-5-carbonitriles with newly synthesized 5-[(2-hydroxyethyl)sulfanyl]- and 5-{[2-(2-hydroxyethoxy)ethyl]sulfanyl}-3-amino-1,2,4-triazoles under heating was studied. It was shown that in the case when the C5 atom of the 1,2,4-triazole ring bears hydroxy(ethoxy)ethylsulfanyl substituents, 5-amino-1,2,4-triazines are formed as the main reaction products, while the ipso-substitution products of the C5-cyano group of the substituted 1,2,4-triazole ring were isolated only as by-products. With a 1,2,4-triazole with a monoethylene glycol fragment at the C5 position, a complex mixture of products was formed.