Reaction of equimolar amount of methylglyoxal with aminoguanidine yielded a mixture of 3-amino-6-methyl-1, 2, 4-triazine (II) and 3-amino-5-methyl-1, 2, 4-triazine (III). They were separated in a pure form via 3-amino-6-methyl-4, 5-dihydro-1, 2, 4-triazine-5-sulfonic acid (IV) and hydrosulfic acid adduct (V) of III. V was easily decomposed to III with boiling water, whereas IV was stable and II was recovered by alkaline treatment. Reaction of II and IV with HCN in water, alcohols, or acetonitrile produced 3-amino-6-methyl- 1, 2, 4-triazin-5 (4H)-one (VI), 5, 5'-bis (3-amino-6-methyl-1, 2, 4-triazyl) (X), 3-amino-6-methyl-1, 2, 4-triazine-5-carboxamide (XI), and 3-amino-5-alkoxy-6-methyl-1, 2, 4, -triazine (XII). Alkylation of the sodium salt of VI with alkyl iodide or dialkyl sulfate yielded 2-alkyl-3-amino-6-methyl-1, 2, 4-triazin-5 (2H)-one (XIII). Reaction of III with 5-nitrofurfural in the presence of sulfuric acid afforded the condensation product, 3-amino-5-[2-(5-nitro-2-furyl)-vinyl]-1, 2, 4-triazine (VII).