The present study aims at assessing the seawater intrusion along the coastal blocks – Parangipettai, Kumaratchi, Kurinjipodi and Bhuvangiri blocks of Cuddalore district, Tamilnadu. Fifty two groundwater samples were collected from the above blocks during May 2017 and analysed for the following parameters / ions, viz., Hydrogen-ion concentration (pH), EC, TDS, Ca, Mg, K, Na, K, CO3 , HCO3, Cl, and SO4. The general quality of groundwater for drinking purpose was presented. To delineate the seawater intrusion in the study area, Ca/Mg, Cl / (CO3 + HCO3), Na/Cl ratios were used. The details of criteria for recognition of saltwater intrusion in coastal aquifers of the study area were presented and discussed. It is observed that sodium or magnesium is the dominant cation and chloride or bicarbonate is the dominant anion in the study area. According to hydro geochemical ratio the study area seems to be contaminated with seawater intrusion and also this contamination is due to marine source of origin.