The present investigation was carried out to transform tomato variety Pusa Ruby using Trichoderma endochitinase (ech42) gene fused with rice a - amylase signal peptide (PSPa-amyech42) and to evaluate the transgenic plants against selected pathogens. Fusion of a - amylase signal peptide to ech42 directs secretion of endochitinase into the intercellular region of plants and thus helps in early control of pathogenic fungi. Cotyledonary leaf discs from green house grown seedlings were co-cultivated with Agrobacterium tumefaciens LBA4404 (pMASGK:: PSPa-amyech42) for 48 hrs. Putative transformants were selected on MS supplemented with kanamycin (40 mg/l). Out of 56 regenerated plants, only 11 plants were positive. Per cent transformation (considering number of PCR positive plants obtained   out of total number of responding explants) ranged from 1.25 to 4.61 among six different batches of explants co-cultivated. Chitinolytic activity in putative transformants and non transformants was measured using crude protein extracts from plants and colloidal chitin as substrate. All the putative transgenic plants (PSPa-amyech42) tested showed significantly higher level (1.58 to 6.37 fold) of enzyme activity compared to non transformants.  In bioassay against Sclerotium rolfsii, transgenic plants showed higher inhibition at both the concentrations of 250 and 500 µg crude proteins compared to non transformants. In detached leaf bioassay against Alternaria solani, per cent leaf area infected in control was 73.7 ± 0.54, while in transgenic lines it ranged from 6.2 ± 0.38 to 17.9 ± 0.73.