Two series of benzofuran-based thiosemicarbazides 7, 8(a-l) are evaluated as P. aeruginosa quorum sensing inhibitors (QSIs). The studied compounds resulted in reduction of violacein production of C. violaceum, at ¼ MIC, up to 26.04 – 67.36%, relative to the reference drug azithromycin (54%). In vitro evaluation of QS and antivirulence activities, at the same concentration, against P. aeruginosa, showed promising inhibitory effect of biofilms formation, bacterial motility and virulence factors production (pyocyanin, and rhamnolipids). Compounds 7a, 7d, and 7k inhibit biofilm formation up to 57.31%, 67.54%, 78.38%, respectively, in addition to > 50% inhibition of hemolysin production. On the other hand, compounds 8a, 8d, 8f and 8k of the bromobenzofuran series showed, 55.66%, 50.67%, 73.34%, 79.93%, reduction in biofilm formation, respectively. Compounds 8d and 8f exhibit > 50% reduction of hemolysin