Abstract: - 1,3,4-thiadiazole nucleus is therapeutically interesting drug candidate as anti-inflammatory, antimicrobial ,anticonvulsant, antihypertensive, analgesic, antiepileptic, antiviral, antineoplastic and antitubercular agents. Therefore thiadiazole derivatives IVa-k were synthesized. The structures of the synthesized compounds were confirmed by spectral data and elemental analysis. The synthesized compounds were screened for antifungal activity by using Minimum Inhibitory Concentration (MIC) by serial dilution method against Staphylococcus aureus ATCC 9144, Becillus Cereus ATCC 11778, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 2853. , Aspergillus niger and Aspergillus flavus.