Plasmids were observed from three strains of Xylella fastidiosa. A restriction map of a plasmid, pXFPW1 of 1.3 kb, isolated from Xyl. fastidiosa strain PWT-22, causing periwinkle wilt disease, was constructed using EcoRI, HaeIII, HinfI, MspI, StyI, and TaqI fragments. No restriction site for BamHI, BglI, DraI, EcoRV, HindIII, PstI, SalI, NcoI, or XbaI was evident. Studies based on the intensity of ethidium bromide staining indicated that there are at least 60 copies of pXFPW1 per genome. pXFPW1 shares a high degree homology with two other plasmids from strains PD82-21 and mul1, the pathogens of Pierce's disease of grapevine and mulberry leaf scorch disease, respectively.