Chitinases are important component of plant defence in response to attack by pathogens. To identify specific chitinase, we constructed a cDNA library using total RNA from a genotype-resistant tomato inoculated with conidia of isolates race 2 of Fusarium oxysporum f.sp. lycopersici (Fol). One chitinase (SolChi) clone was isolated and sequence analysis shows that the cDNA clone SolChi encodes an acidic isoform of class III chitinase. Southern blotting indicated that SolChi was present only once in the tomato genome. Real-time quantitative RT-PCR assay show that the expression of this gene is induced upon infection with Fol, and the accumulation of transcripts for this R protein was rapid in the resistant genotype during the first 24 h. A putative role for chitinase in tomato is defence against fungal pathogens.