Parastagonospora (syn. ana, Stagonospora; teleo, Phaeosphaeria) nodorum (Berk.) Quaedvlieg, Verkley & Crous is the causal agent of Stagonospora nodorum blotch (SNB) on durum and bread wheat. This fungus is a major wheat pathogen in most wheat-growing areas of the world. A collection of 193 Parastagonospora isolates were collected from naturally infected wheat fields of four provinces from Iran: Kogiluyeh and BoyerAhmad, Khuzestan, Golestan and Fars. To obtain P. nodorum isolates, leaf and ear segments were attached to glass slides with tape and kept under high humidity conditions until the pycnidia produced cirri containing pycnidiospores. Single oozing cirri from lesions were isolated with a flame-sterilized needle. Isolates were grown on Petri dishes containing Yeast Sucrose Agar (YSA, 10 g/L Yeast Extract, 10 g/L sucrose, 1.2% agar) amended with 50 μg of kanamycin. Single colonies were transferred to flasks containing 50 ml Yeast Sucrose Broth (YSB, 10g/L Yeast Extract, 10g/L sucrose) and grown on an orbital shaker for 5 to 7 days at 120 rpm at 18°C. DNA extraction was carried out by Murray and Thompson (1980) method. We PCR-screened 193 isolates of P. nodorum from Iran for the presence or absence of the SnToxA, SnTox1 and SnTox3 genes with gene specific PCR primers. Results from PCR assays showed that SnTox3 was present at lower frequency than the other two effectors. SnToxA and SnTox1 were found at a frequency >94%. All three effectors were present at high frequencies between 72% -97%. Thus, the PCR method can be used in various detections of toxin-producing fungi.