The study was carried out to assess the water quality parameters of the Agniyar estuary, Tamil Nadu, India from August 2015 to April 2016. The monthly variations showed minimum and maximum value water temperature (24.52 – 32.15˚C), turbidity (47.75 – 59.15 cm), pH (7.62 – 8.4 ppm), dissolved oxygen (3.35 to 6.19 mg/L), salinity (18.27 - 25.57 ppt), calcium (95.15 – 146.9 mg/L, nitrate (0.32 – 0.51 mg/L) and ammonia (0.13 – 0.24 mg/L) respectively.. The minimum and maximum values of above parameters were observed during the study period of August 2015 to April 2016 in the Agniyar estuary.