Rice blast disease, caused by Pyricularia grisea, is an important rice disease in Iran and throughout the world. Out of 150 infected samples collected from paddy fields of Guilan province, 57 fungal isolates were isolated for which PDA and W.A media were used. Morphological characteristics were used for identification of these fungi. It was found out that the isolated fungi were belonged to Pyricularia grisea, Ulocladium alternariae, Ulocladium cf. alternariae, Ulocladium cf. consortiale, Ulocladium sp., Curvularia pallescens, Preussia sp., Epicoccum sp. and Trichoderma harzianum. According to pathogenicity tests, all isolates of P. grisea were proved to be pathogenic on rice and fungal isolates belonging to other fungal genera which did not cause disease on rice were selected for biological control studies and to do so, were used different methods. Results showed that eight isolates of T. harzianum, U. cf. consortiale, Ulocladium sp., Epicoccum sp., Preussia sp., C. pallescens, U. alternariae and U. cf. alternariae, had the highest inhibitory effect in mycelial growth of P. grisea, respectively. In hyperparasitism test, hyphae of T. harzianum did not coil around the mycelium of P. grisea. In these experiments, T. harzianum and U. cf. consortiale isolates had the highest inhibitory effect on growth rate of P. grisea and was known as the most effective isolates. Based on results, volatile metabolites method was best method in control of P. grisea in vitro.

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