The rice blast, caused by fungus Magnaporthe oryzae, is a major constraint to the world food security. Hyphal growth is the foundation of fungal development and proliferation of fungi. To investigate genes involved in hyphal growth of this fungus, digital gene expression tag profiling was used to compare a previously generated temperature-sensitive mutant which defect at hyphae growth and reduction on pathogenicity, with its related wildtype strain. 416 genes were detected as differential expression, 178 of which were specifically expressed in Guy-11 but down-regulated expression in the mutant. Functional classification analysis revealed the phenotype mutation may be mainly caused by a defection in translational and vacuole-related processes. The results and the protocol used will improve our knowledge on morphogenesis and promote the further study on M. oryzae pathogenesis.