Studies were undertaken to determine the defensive role played by phenolic acids present in peel and pulp of mango against fruit fly, Bactrocera dorsalis (Hendel) in different mango cultivars. The fruit fly infestation exhibited a significant negative relationship with total phenolics. Gallic acid, Proto-catechuic acid, p-OH benzoic acid, p-coumaric acid, ferulic acid, o- Coumaric acid and t- Cinnamic acid were the phenolic acids recorded in mango peel. Very high gallic acid was noticed in Langra (2569.43 μg/ml), followed by EC 95862 (7153.99 μg/ml). and Dusheri and Totapuri also showed considerably higher gallic acid conents while Banganapalli recorded the lowest content (193.0 μg/ml). Among the varieties, Banganapalli (69.20%) had significantly higher infestation whereas EC 95862 (1.40%) and Langra (0.00%) had lower infestation at 100 per cent maturity. The defensive mechanism exhibited by the phenolic acids in resistant varieties was evident from these results and confirmed through multiple regression