Direct seeded rice is a boon to farmers where the water release from the reservoir is delayed. Nitrogen fertiliser management is one of the strategies bto rectify the nutrient-related issue in Direct seeded rice. The present study aimed to optimize the nitrogen dose for direct-seeded rice in the new and old Cauvery delta zone of Tamil Nadu. Field experiments were conducted during kuruvai and samba seasons at Tamil Nadu Rice Research Institute, Aduthurai and Agricultural research station Thanjavur representing old and new Cauvery delta regions during 2019-20 and 2020-21. Totally from eight experiments, the results of four field experiments in each location revealed the highest grain yield in the treatment T6 -application of 150 kg Nha-1 (5596kg/ha) which was statistically on par with treatment T5 -125kg N/ha (5326 kg/ha) in old delta and new delta. The higher grain yield was recorded in the T6 (5140 kg/ha), statistically on par with T5 (4550 kg/ha). The higher available nitrogen content of 312 kg/ ha,292 kg/ha was recorded for N application @ 150kg/ha, which was statistically on par with 309 kg/ha and 289 kg/ha, respectively, both the kuruvai and samba seasons for N application of 125 kg/ha. In the new CDZ, the same trend was followed as that of the old delta. Based on economics, N applied @125 kg/ha recorded a higher BC ratio for direct-seeded rice. For the benefit of farmers of both deltaic regions, the nitrogen application of 125 kg ha-1 for direct-seeded rice is recommended.