A new series of quinazolinones containing hydrazone moiety were synthesized, and their inhibitory activities on urease were assessed in vitro. Most of the compounds exhibited potent urease inhibitory activity. Among the synthesized compounds, molecule 4a bearing furan ring has the best inhibitory effect against urease with IC50 = 2.90 +/- 0.11 mu g/mL. Compounds 4f, 4g, 4h, 4i, and 4j have hydroxy group on phenyl ring. Compound 4i is the most active inhibitor among these compounds with IC50 = 5.01 +/- 0.10 mu g/mL, which has 3-Cl and 4-Br on phenyl ring. Also, newly synthesized compounds had been tested for their antimicrobial effects against three of Gram-positive bacteria (Bacillus cereus 702 Roma, Staphylococcus aureus ATCC 25923, and Streptococcus pyogenes ATCC 19615) and three of Gram-negative bacteria (Escherichia coli ATCC 25922, Proteus vulgaris ATCC 13315, and Pseudomonas aeruginosa ATCC 27853). Antimicrobial activity results show that compounds 4a, 4h, 4j, 4f, and 4l have the lowest minimum inhibitory concentration (MIC) value of 1000 mu g/mL to all tested bacteria. The other compounds have the MIC value of >1000 mu g/mL to all tested bacteria.