Bacterial blight of rice caused by Xanthomonas oryzae pv.oryzae is becoming a major production constraint worldwide. In India, the disease has been reported to be major threat causing yield loss. In the state of Kerala disease is appearing in an epidemic nature during kharif season in recent years. A survey has been carried out to assess the intensity of the disease in major rice growing districts of the state and to isolate pathogen from different locations. The predominantly cultivated rice varieties in farmers field such as Uma and Jyothi were affected in all the districts surveyed viz., Palakkad, Malappuram and Thrissur. Both kresek as well as leaf blight symptoms were observed. The severity of the leaf blight upto 95.10 per cent was recorded in variety Uma and 90.5 per cent in variety Jyothi. kresek symptom was observed in Palakkad, Malappuram and Thrissur districts in varieties Jyothi, Uma and Ponmani. In Palakkad district the disease severity ranged from 5.28 to 50.80 per cent. In Malappuram district kresek symptom was observed in Ponmani and the severity ranged from 10.13 to 15.05 per cent. In Thrissur district kresek symptom was recorded in variety Jyothi and Uma, the disease severity ranged from 10.35 to 50.15 per cent. The 168 Xanthomonas oryzae pv.oryzae isolates from different locations of major rice growing tracts varied in their virulence upon inoculation to the susceptible variety Jyothi. The disease severity caused by the isolates ranged from score 5 to score 9. The disease reaction caused by the Xoo isolates varied widely indicating the variability.The genetic variability was further tested by DNA fingerprinting of representative isolates from different districts, which showed high variability among the isolates. Further studies on pathotyping of the Xoo isolates are needed to understand the genes/ gene combinations effective for imparting broad spectrum resistance to rice varieties against prevailing pathogen population of the state.