Zymoseptoria tritici is the pathogen responsible for Septoria tritici blotch (STB) disease in wheat, causing significant yield losses during some years. This disease is observed in wheat production areas in our country as in many regions of the world. In this study, STB diseased wheat leaves were collected from six geographical regions in wheat cultivation areas of Turkey during 2013 and 2014 production seasons. A total of 103 single spore isolates obtained from the collection of Z. tritici population were chosen as representative for testing of their mating type. The isolates were evaluated for mating type (MAT) idiomorph frequency by multiplex PCR using Z. tritici specific MAT primers. The prevalence of mating types was found to be 48.5% (50) and 51.5% (53) for Mat1-1 and Mat1-2, respectively. Chi-square test was used to assess that two mating type scores are at equal frequencies. The study affirms the hypothesis that Z. tritici is reproducing sexually and spread via airborne ascospores aside from rain splash dispersed asexual spores in Turkey. Genetic recombination during sexual mating has a potential to generate more virulent pathotypes of Z. tritici.