Abstract: The Indian Ocean tsunami, triggered by the Sumatra-Andaman earthquake on December 26, 2004, caused approximately 2,30,000 casualties and widespread damage to infrastructure in several Indian Ocean rim countries. In fact, the 2004 tsunami was one of the strongest and deadliest ever recorded in terms of magnitude, which put into perspective the need to set up an early warning system for tsunamis in India. Following the 2004 tsunami, the Indian Tsunami Early Warning System (ITEWS) was established to provide early warnings on impending tsunamis triggered due to earthquakes in the Indian Ocean. This article describes various components of ITEWS, the decision support system and the bulletins. It also discusses issues, challenges and future developments.