In order to search novel antimicrobial and antifungal agent series of new 5-phenyl-1-H-1,2,4-triazol-3-thione derivatives bearing different aldehydes moieties were designed and synthesized through multistep reactions. The newly synthesized compounds were evaluated for in vitro antibacterial activity against S. aureus, E. species, E. coli, P. auriginosa, and antifungal activity against A. niger, C. albicans using broth micro dilution method. Ciprofloxacin and Fluconazole were used as standard for antibacterial and antifungal screening respectively. Among the compounds 4a-4f, particularly, compound 4b and 4d showed highest antibacterial activity as compared to the other derivatives against all bacterial species with a MIC of 200 μg/ml. Compound 4d emerged as the most effective antifungal agent against C.albicans and A.niger.