Several 1-aryl-5-hepta-O-benzoyl-β-D-lactosyl-2-S-benzoyl-2, 4-isodithiobiurets have been synthesized by the interaction of hepta-O-benzoyl-β-D-lactosyl isothiocyanate with several 1-aryl-S-benzyl isothiocarbamides. These compounds were screened for their antibacterial and antifungal activities against–Escherichia coli, Proteus vulgaris, Staphylococcus aureus, Salmonella typhimurium, Klebsiella pneumonie, Psudomonasaeruginosa, Aspergillus niger and Candida albicance.  The newly synthesized compounds have been characterized by analytical and IR, 1H NMR and Mass spectral studies. These compounds show appreciable activity towards these microorganisms.