Quorum sensing (QS) and biofilm formation are important mechanisms related to antibiotic resistance of many pathogens. Alternative treatments are needed to prevent recurrent or chronic infections caused by multi-resistant pathogens. Therefore, the aim of this study is to investigate and compare the inhibitory potential of the dietary phytochemicals: curcumin, quercetin, apigenin, pyrogallol, gallic acid and luteolin against QS of and biofilm formation by Chromobacterium violaceum ATCC 12472 and the swimming and swarming abilities of Pseudomonas aeruginosa PAO1. Anti-QS potential of the phytochemicals was evaluated qualitatively and quantitatively using C. violaceum via the disk diffusion assay based on violacein pigment inhibition at the subminimal inhibitory concentrations ranging from 46.87 to 750 µg/mL. The results of anti-QS and antibiofilm activities on C. violaceum demonstrated that all the phytochemicals except pyrogallol and gallic acid inhibited violacein production (from (11.0±0.1) to (88.2±0.1) %) in a concentration-dependent manner.; Međustanična komunikacija (engl. quorum sensing) i formiranje biofilma imaju važnu ulogu u mehanizmu otpornosti mnogih patogenih mikroorganizama na antibiotike. Za sprečavanje povratne i kronične upale uzrokovane višestruko otpornim patogenim bakterijama moraju se koristiti druge vrste liječenja. Stoga je svrha ovoga rada bila ispitati i usporediti inhibicijski učinak fitohranjiva, i to: kurkumina, kvercetina, apigenina, pirogalola, galne kiseline i luteolina na međustaničnu komunikaciju i sposobnost formiranja biofilma bakterije Chromobacterium violaceum ATCC 12472, te pokretljivost i rojenje bakterije Pseudomonas aeruginosa PAO1. Sposobnost fitohranjiva da inhibiraju međustaničnu komunikaciju procijenjena je kvalitativno i kvantitativno metodom disk difuzije pomoću bakterije C. violaceum. Ta se metoda zasniva na inhibiciji sinteze violaceina pri subminimalnim inhibicijskim koncentracijama fitohranjiva od 46,87 do 750 µg/mL. Rezultati pokazuju da sva fitohranjiva, osim pirogalola i galne kiseline, inhibiraju proizvodnju violaceina u bakteriji C. violaceum, i to od (11,0±0,1) do (88,2±0,1) %, ovisno o koncentraciji. Osim toga, fitohranjiva su bitno (p<0,05) inhibirala formiranje biofilma, i to od (1,38±0,08) do (84,2±0,2) %.