A general method for the preparation of substituted azolo-as-triazines is reported. The various alpha-aminoazoles (3-aminopyrazole, 3-amino-s-triazole, 5-amino-v-triazole, 2-aminoimidazole, 4(5)-aminoimidazole, and their substituted derivatives) were diazotized and coupled with active methylene reagents (beta-diketones, beta-keto esters, beta-keto acids, ethyl cyanoacetate and malononitrile) to afford intermediates which were then cyclized in methanol, acetic acid, or benzene. The cyclized products were the corresponding pyrazolo[2,3-c]- (2), s-triazolo[2,3-c]- (3), imidazo[3,4-c]- (4), v-triazolo[1,2-c]- (5), and imidazo[3,4-c]-as-triazines (6) with substituents such as amino, alkyl (or hydrogen), ester, ketone, or nitrile, depending on the methylene reagent used. Of the 28 compounds synthesized (representative of the five heterocycles) six, with various substituents, exhibited specific in vitro antimicrobial activity. Compounds 2b and 2d inhibited the gram-negative bacterium Pseudomonas, 3a, and 5a inhibited the gram-positive Staphylococcus, 2h inhibited the dermatophyte Trichophyton, and 2c inhibited the yeast Candida in the MIC (minimum inhibitory concentration) range of 0.40-0.16 mumol/ml.