El Niño Southern Oscillation (ENSO) is one of the most important drivers of climate variability. To study the impact of ENSOonseasonal rainfall over Tamil Nadu, historical weather data for the period of 43 years (1971-2013) were categorized based on the ENSO episodes and the analysis was performed for assessing ENSO linked climate variability (onset and cessation) for North east monsoon rainfall (NEM: October - December) and rainfed cropping period (September - December) over Tamil Nadu. Onset was determined using the pentad analysis performed from 1st October through 31th October, considering first pentad with quantum of 10 mm of rainfall followed by four consecutive pentads of 10 mm of rainfall per pentad. The same approach was followed for deciding the onset of sowing rains for rainfed cropping period starting from 1st September to 10th October. In NEM and rainfed cropping period, cessation of monsoon was seen in December month. If the cessation didn't occur during December, the cessation time was noted in November month and the season was considered as the last day that received rainfall amount of > 2.5 mm. In NEM, higher per cent of years had onset in the slot from 1st to 5th of October (65.0, 63.4, 65.2 per cent of El Niño, La Niña and Neutral years, respectively). Few years were in neutral phase (26.3 %) and in El Niño (19.4 %) andunderLa Niña (15.2%) phase the results showed the onset happened between 6th and 10th of October. In most of the El Niño years (68 %), sowing rain occurred during 1st week of September (1st to 7th September), while in 40 per cent of the La Niña years sowing rain was delayed by one week and received during 2nd week of September. Cessation was earlier in most of the La Niña years as compared to El Niño and neutral years. [ABSTRACT FROM AUTHOR]