Tomato (Lycopersicon esculentum Mill.) is one of the most remunerative and widely grown vegetables in the world. Tomato has ranks second next to potato in world acreage, but it has rank first among processing crops. In the present study, tomato plants treated with Rhizophora apiculata as seed treatment at 15 % and as foliar spray at 30 and 45 days after treatment (DAT), co-inoculated with the Alternaria solani pathogen, recorded maximum activity of the defense related enzymes and PR proteins including; peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), catalse, chitinase and β- 1,3 glucanses. Induction of these defense enzymes was studied in vivo in treated tomato plants grown in the greenhouse. Moreover, the healthy control tomato plants also showed slight increase in activities of all these defense enzymes up to four days, and thereafter showed gradual decline. The aim of the present investigation was to access the induction of the defense enzymes and PR- proteins in tomato plants infested with A. solani, through the application of R. apiculata extract. Accordingly, we can reduce the incidence of early blight disease in these tomato plants. Current findings recorded the earlier and higher accumulation of the defense enzymes and PR-proteins mainly; PO, PPO, PAL, β- 1, 3 glucanse and chitinase in tomato plants, resulting in significant reduction in early blight infection.