Abstract: AIM　To synthesize a series of new fused heterocyclic compounds containing 1,2,4-triazole and 1,3,4-thiadiazole rings. METHODS and RESULTS　Nine new fused heterocyclic compounds have been synthesized by the reaction of 3-p-nitrophenoxymethyl-4-amino-5-mercapto-1,2,4-triazole with aromatic aldehydes in the presence of acid. The reaction conditions for the synthesis have been investigated. The structures of the synthesized compounds were confirmed by elemental analysis, IR, ¹HNMR and MS. All of the compounds were screened for their biological activities. CONCLUSION　The results show that some compounds (2c, 2d, 2e, 2f) showed strong antibacterial activities.