Abstract: The present study was carried out to investigate the hydrographical parameters, nutrients, total coliforms and total heterotrophic bacteria populations in water and sediment samples of Mullipallam creek in Muthupettai mangroves. The range of hydrographical parameters in water samples viz., atmospheric temperature (28.5-32.2°C), surface water temperature (28.2-31.7°C), salinity (31-34‰), pH (8.0-8.3) and dissolved oxygen (2.95-3.52 mg-1) and in nutrients, inorganic phosphate (0.322-0.810 μmol-1), total phosphorus (1.312-3.239 μmol-1), nitrite (0.858 to 1.384 μmol-1), nitrate (1.937-5.133 μmol-1), silicate (16.272-21.237 μmol-1), ammonia (0.068-0.191 μmol-1) and total nitrogen (23.921-26.919 μmol-1) in water samples. The level of nutrients in the sediment samples, total nitrogen was varied from 3.70 to 8.96 μg-g, total phosphorus was ranged from 0.947 to 2.872 μg-g and total organic carbon was varied between 3.721 and 6.576 mg-g. The microbial population of present investigation was revealed that a total of nine bacterial coliforms were recorded, which includes of seven gram-negative forms such as Vibrio cholerae, V. parahaemolyticus, Escherichia coil, Klebsiella pneumonae, Shigella dysenteri, Streptococcus faecalis and Pseudomonas aeruginosa. The total of seven heterotrophic bacterial populations were recorded of which Vibrio sp. and Escherichia coli were from to be the dominant species followed by Shigella sp., Pseudomonas sp., Klebsiella sp., Salmonella sp. and Streptococcus sp.