Abstract An improved procedure is suggested for preparing 2-amino-1, 2, 4-triazolo [1, 5-a] pyrimidines from 3, 5-diamino-1, 2, 4-triazole and unsaturated aromatic ketones, with acetyl protection of the amino group in the step of oxidation of 2-amino-4, 7-dihydro-1, 2, 4-triazolo [1, 5-a] pyrimidines.