Bean hypocotyls, pea pods and tomato fruits were tested for phaseollin, pisatin and rishitin production when challenged with the phytopathogenic bacteria Erwinia carotovora; Pseudomonasphaseolicola, P. pisi and P. solanaeearum, and their isolated extracellular polysaccharides. All bacteria induced phytoalexin accumulation, whereas only phaseollin and pisatin, but not rishitin, were elicited by EPS. The inhibitory effect of these three phytoalexins on bacterial growth was studied in liquid medium; whereas phaseollin and pisatin strongly inhibited growth, only a slight inhibitory effect resulted from the presence of rishitin in the medium.