Heterocyclic systems comprising quinazolinones have been explored to a major extent in last few decades due to its chemotherapeutic and antimicrobial potential. Quinazolinone is a bicyclic compound containing benzene ring fused with pyrimidine ring. Microbiology is the study of microscopic organisms such as bacteria, viruses, fungi and protozoa. This discipline includes fundamental research on the biochemistry, physiology, cell biology, ecology, evolution and clinical aspects of microorganisms, including the host response to these agents. Bacterial resistance to existing drugs is a growing problem in the world. The antibacterial and antifungal activity data of 2,3-disubstituted 4(3H)-quinazolinone derivatives (6A-6J) indicated that the compounds have significant inhibitory activity on all the bacterial and fungal strains at both 50 (0.05 ml) and 100 (0.1 ml) dose levels when compared with standard. Among all the compounds tested, compounds 6A, 6B, 6C and 6D possessed maximum activity in both fungal as well as bacterial strains. These compounds possessed the halogens on the aromatic ring and thus reveal the positive contribution of electron withdrawing groups to the antibacterial activity.