Forty-two natural essential and edible oils were tested for their ability to inhibit bacterial QS to create a comprehensive database of candidate inhibitor compounds which may provide significant option for treatment of bacterial infections. QS inhibitory activities of oils were screened using biomonitor organisms; Quorum Sensing Inhibitor Selector strain1 (QSIS1) and Chromobacterium violaceum strain CV026, C. violaceum strain VIR07, C. violaceum strain ATCC 12472 and opportunistic pathogen Pseudomonas aeruginosa PAO1, clinical isolate of P. aeruginosa (PCI). While eleven of tested oils were found to be positive for QSIS1; Rose, clove, chamomile essential oils and pine turpentine exhibited significant decrease in violacein production for Chromobacterium strains tested at very low concentrations and showed anti-biofilm activity in clinical isolate of P. aeruginosa (PCI). The chemical compositions of rose, clove, chamomile essential oils and pine turpentine were determined by GC-MS. Results of this study showed that there are noteworthy QSI compounds in the rose, clove, chamomile essential oils and pine turpentine and this potential could be important treatment strategy for Pseudomonal infections.