Some novel derivatives of acylhydrazine such as; 5-substituted-2-mercapto-1,3,4-oxadiazoles 2a-g their corresponding S-esters 3a-g, amides 4a-g and benzenediazasulfonamides 6a-d have been prepared.Twenty four synthesized compounds were screened in vitro for their antibacterial and some for their antifungal activities.Minimum Inhibitory Concentration (MIC) values of all the twenty four synthesized compounds were also determined.Some of the synthesized compounds exhibited significant antimicrobial activity.