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Not AvailableTwo hundred and sixty-six grape genotypes maintained at National Active Germplasm Site at ICAR-National Research Centre for Grapes, Pune, were screened for their reaction against anthracnose disease. Among them, sixty one genotypes were identified as resistant sources for anthracnose disease. All major commercial cultivars were found susceptible. The levels of biochemical constituents in the leaves of 10 resistant and 10 susceptible genotypes were examined for their possible association with disease resistance which can be used as a biochemical marker. Before challenge inoculation with the pathogen the levels of total phenols (21.32 mg/g), flavonols (10.93 mg/g), and peroxidase activity (0.226 U/ml) were significantly higher in anthracnose resistant genotypes. After challenge inoculation with the pathogen, apart from total phenols (25.91 mg/g), flavonols (13.35 mg/g), and peroxidase activity (0.371 U/ml), the resistant genotypes also showed higher levels of flavonoids (9.55 mg/g), flavon-3-ols (1.94 mg/g) and polyphenol oxidase activity (0.0471 U/ml), but the per cent increase data was significant only for total phenols, flavonoids, polyphenol oxidase and peroxidase. Five of the selected anthracnose resistant (or susceptible) genotypes were also resistant to downy mildew disease while, the other five were susceptible to downy mildew, thus, classifying the 20 genotypes into 4 groups. Interestingly, only peroxidase activity was significantly higher in the 2 anthracnose resistant groups as compared to the 2 susceptible groups. Furthermore, cluster analysis confirmed that, peroxidase activity was the only clear indicator of anthracnose resistance and can be used as a biochemical marker.Not Availabl