Wheat is one of the most important crops in Turkey. Production of this crop is constrained by the disease Septoria leaf blotch, which is a major bottleneck in wheat production in the Eastern Mediterranean Region of Turkey. In this study, 260 different wheat fields were surveyed for the estimation of prevalence and severity of Septoria leaf blotch. Out of 100% of the total wheat crop fields, 58.91% were infected with this disease. The mean value of Septoria leaf blotch virulence was 11.62%. Out of 142 diseased wheat crop samples, 74 isolates were used for the pathogenicity test. Forty-seven isolates from Adana, 3 isolates from Mersin, 3 isolates from Osmaniye, 14 isolates from Hatay, and 7 isolates from Kahramanmaraş provinces were cultured on PDA plates. The cause of disease agent was identified based on microscopic observation of morphological structure and molecular analysis methods. Consequently, total 15 virulent isolates, 3 isolates from each province were sequenced for 5? and 3? ends of ITS of rDNA and nBLAST of the ITS sequences revealed that Zymoseptoria tritici was the agent of Septoria leaf blotch. The highest disease prevalence (87.99%) was recorded at Adana and followed by Osmaniye with 87.44%, Kahramanmaraş (43.59%), Mersin (42.68%), and Hatay (26.03%).