In the present study, 5-(4-substituted phenyl)-1, 2, 4-triazole-3-thiol (5a-e) were synthesized from 5-(4-substituted phenyl)-1, 3, 4-oxadiazole-2-thiol (4a-e) and their structures were confirmed by IR, NMR, Mass spectral and elemental analysis. These synthesized compounds were screened for the antimicrobial and cytotoxic activities. The results indicated that, compound 5(a) and 5(b) showed the highest antibacterial activity. Compound 5(d) and 5(e) were observed to be the most potent antifungal agents. The structure activity relationship discovered that the presence of electron withdrawing and electron donating substituents at para position of phenyl ring of synthesized compounds enhance the antibacterial and antifungal activities, respectively. Further, the results of cytotoxicity studies on breast cancer cell line (MCF-7) suggested that active antimicrobial agents 5(a), 5(b), 5(c), 5(d) and 5(e) are accompanied with low cytotoxicity. The biological profiles of these 1, 2, 4-triazoles would be a fruitful matrix for further development of safe and efficacious compounds.