Today, we have important knowledge of quorum sensing (QS) for bacterial pathogenesis and spoilage of food, thus research has concentrated on inhibiting QS using natural products. This chapter will give an update on recent advances in anti-QS research toward several reporter strains, covered by literature data from the last decade. Inhibitory potential of selected plants, mushrooms, and pure compounds and their inhibitory potential against several QS regulated traits (production of virulence factors, antibiofilm activity, etc.) is summarized and briefly discussed in the text. Presented data indicate that various natural products, most likely from groups of tannins, alkaloids, polyphenols, and terpenes, that may have a profound impact on gene regulation of several pathogenic microorganisms, including Pseudomonas aeruginosa, Chromobacterium violaceum, Vibrio harveyi, etc. Yet their true potential for treating bacterial infections with newly developed antimicrobial agents based on QS inhibition is still to be elucidated.