Bacterial leaf streak symptoms on wheat are elongated translucent, water- soaked lesions were observed in five farms in Al-Karj region, Riyadh, Saudi Arabia Physiological characters of three isolates obtained from naturally diseases wheat plants confirmed as Xanthomonas translucens pv. translucens Isolates (i.e.XW1,XW2 and XW3). They characterized as Gram negative, short rod-cell with yellow- pigmented colonies tests which were positive were: motility, esculin hydrolysis, hypersensitivity on tobacco and utilizing arabinose and mannose. Tests which were negative were: Kovacs' oxidase, arginine dihydrolases, nitrate reduction and starch hydrolyse. Furthermore, the identification was confirmed by using Biolog system.  Pathogenicty tests revealed that all isolates were able to induce leaf streak and black chaff symptoms when the bacterial suspension (10⁸CFU) At inoculums density lower than 10⁵ CFU/ml, no visible lesions were observed on the leaves segments after 14 days from inoculation. At inoculums concentrations higher than 10⁶ CFU/ml, the number of lesions did not increase significantly with the increase in inoculum concentration. Greenhouse tests showed that cultivar Yocora rojo was susceptible to bacterial streak and black chaff. Yield loss was recorded 11.60 % compared with the other cultivars.