The aim of this study was to isolate, identify and analyze the diversity of the causative agents of crown galls and hairy roots from symptomatic plants ofVaccinium corymbossumby means of biological, biochemical and molecular tools. All the bacteria isolated from blueberries (n = 78) were found to beAgrobacteriumsince they grew on three differential media, provoked cell and/or root proliferation on Kalanchoe, and contained a 730bp partial sequence that codes for virulence genes within thevirC operon found on Ti and/or Ri plasmids. Isolates were highly variable considering the ERIC-PCR patterns as well as biochemical reactions and were all represented by 7 different restriction patterns of the 16SrDNA. While most of the isolates belonged toAgrobacteriumbv. 1 (n = 33) orAgrobacteriumbv. 2 (n = 31) only fourteen wereAgrobacterium rubi.A representative isolate of each of these three groups was further identified by sequencing the approximately 400bp 16SrDNA. We concluded thatVacciniumplants are particularly susceptible toAgrobacteriumbv. 1,Agrobacteriumbv. 2, and also toAgrobacterium rubi.To our knowledge this is the first survey ofAgrobacteriumaffecting blueberries in Argentina.