Sixteen fungi were isolated from leaves of mangrove plants of Sundarbans, India. Their growth response to tannin, extracellular pectolytic enzyme (PE) activity and degree of inactivation of PE due to presence of tannin were tested in vitro. Tannin (0.2% inhibited growth of all test fungi, but low concentration (0.05%) stimulated growth of three fungal species. Enzyme activity in culture filtrates of fungi were also assayed. Phomopsis sp. cf. commelinae and P. clerodendrumii showed maximum (99%) while Exserohilum rostratum exhibited minimum (13%) reduction in viscosity of their respective culture filtrates without tannin. Among 16 fungi, Chaetomium globosum, Curvularia senegalensis and E. rostratum were highly sensitive to tannin with a very low PE activity. Significant inactivation of PE by tannin (0.2%) was recorded for all fungi which was maximum (80-90%) for tannin sensitive fungi.