Thirty isolates of Xanthomonas campestris pv. vesicatoria (Xcv) from Tanzania were evaluated for sensitivity to copper sulphate (CuSO 4 :5H 2 0) using dilution plate counts. Ninety-three percent (28/30) of the isolates produced countable colonies on nutrient glucose agar amended with 0.8 mM CuSO 4 . All the Xcv isolates (7/7) from Arusha (northern Tanzania) grew on the copper medium. Isolates of the pathogen from Iringa (southern Tanzania) produced variable results (15/21). However, neither of the two Xcv isolates from Morogoro (Eastern Tanzania) grew on the copper medium. These results indicate long-term exposure of Xcv isolates from Tanzania to selection pressure for copper tolerance.