Chitinases produced by mycoparasites play an important role in disease control in plants. To explore the functions of chitinases in Trichothecium roseum, we cloned a new chitinase gene named Trchi1 from T. roseum by RT (reverse transcription)-PCR techniques. The T. roseum gene, Trchi1, contains an 1278-bp ORF that shares 76 % similarity with chitinase from Bionectria ochroleuca (ABV57861 3G6L_A). A plant expression vector, containing the Trchi1 gene driven by the CaMV35S promoter, was constructed and transformed into tobacco via Agrobacterium tumefaciens. Southern blot analysis showed that Trchi1 was integrated into the tobacco genome. Total chitinase activity in Trchi1-transgenic tobacco leaves was enhanced 2.2- to 5.8- times with respect to non-transgenic leaves. Transgenic tobacco plants transformed with the Trchi1 gene had increased resistance to Alternaria alternata and Colletotrichum nicotianae.