Eight new 2-[(3,4-dihydro-3-2H-1,4-benzoxazin-2-yl) methyl]-5-(alkyl/arylthio)-1,3,4-oxadiazoles (IV) have been synthesized from 2-[(3,4-dihydro-3-oxo-2H-1, 4-benzoxazin-2-yl) methyl]-5-mercapto-1,3,4-oxadiazoles (III), on reaction with alkyl/aryl halides. The intermediates (III), on the other hand have been prepared from (3,4-dihydro-3-oxo-2H-1,4-benzoxazin-2-yl) acetic acid hydrazides (II) by the action of carbon disulfide in presence of potassium hydroxide. The title compounds have been characterized by their analytical and spectral data and screened for antibacterial and antifungal activities.