A method for the preparation of pyrazolo [3, 4-hl pyridines, i pyrazolo [1, 5-al pyrimidine and triazolo [1, 5-al pyrimidines from aminopyrazoles and amino triazoles was developed. 5-Amino-3- methyl-1-phenyl pyrazole when reacted with benzaldehyde give the Schiff base which on reaction with acetophenone gives the corresponding pyrazolo 13, 4-hJ pyrimidines (i). The reaction of 3- amino-4-cyanopyrazole under similar conditions gave nitrogen bridgehead 11, 5-al in the form of pyrazolo [1, 5-al-pyrimidines (ii) while 3-amino-triazole and 3-amino-5-phenyl-triazole also undergo cyclization to give the condensed systems, pyrazolo [1, 5-al pyrimidines (ii) and triazolo [1, 5-al pyrimidines (iii) in good yields. II and III were isolated as their dihydroproducts. The mechanism for the formation of these products is also proposed. The reaction products were characterized through their IR, PMR and mass spectra or elemental analysis. The products obtained from these reactions were also tested for antibacterial activity.