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Seeds of Iraqi wheat cultivars and the international differential set cultivars of common bunt were inoculated with teliospores of bunt pathogen that had been collected from different regions of Iraq. Results revealed pathogen diversity among the population used. Thediversity was reflected in the host reaction of Iraqi cultivars to the pathogen isolates. All the Iraqi cultivars used such as Madaien (Neda), Rabeea, Tammoze 3, Abo-Ghraib 3, IPA99, Latifiya, Tammoze 2, Oor (Melad), Adnaniya and Araz showed susceptible reaction. Disease incidence of all these cultivars except Adnanyia were less than 10% when their seeds were inoculated with the isolate BU4 which had been isolated from Saief Saad-Kut province. Isolate BU7 isolated from Al-Shahabi region, close to the Iranian borders, caused high disease incidence on all Iraqi cultivars used (29.03-91.48%), thus BU7 was the most virulent isolate followed by Tuwaitha isolate (BU1). Inoculating wheat cultivars carrying Bt genes (Differential set) with nine teliospores isolates confirmed the pathogen diversity in Iraq. Six isolates overcame bunt resistance genes Bt0 and five of them overcame both Bt14 and Bt15. In contrary to all Bt genes, five of them, namely Bt5, Bt7, Bt8, Bt9 and Bt10 proved to be effective. Disease incidence on wheat cvs. carrying those genes was less than 10%.