Marundeeswarar Temple or Oushadheeshwar Temple is a Hindu temple dedicated to the deity Shiva. Shiva is worshipped as Marundeeswarar, and is represented by the lingam. His consort Sati is depicted as Anjanakshi. The presiding deity is associated with the 7th century Tamil Saiva Nayanars Sundarar. The temple is counted as a twin temple along with Kachabeswarar temple, the place where Lord Vishnu did penances to Lord Shiva to incarnate into his Kachaba (Tortoise) Avatar.

The temple complex covers an area of one acre and all its shrines are enclosed with a granite concentric rectangular walls. The temple has a number of shrines, with those of Marundeeswarar and his consort Irulneeki Thayar being the most prominent.

The temple has three daily rituals at various times from 6:00 a.m. to 8:30 p.m., and four yearly festivals on its calendar. The Brahmotsavam festival is celebrated during the day of the Magam (February - March) is the most prominent festival.

The original complex is believed to have been built by Cholas, while the present masonry structure was built during the 16th century. In modern times, the temple is maintained and administered by the Hindu Religious and Charitable Endowments Department of the Government of Tamil Nadu.

As per Hindu legend, Anjanakshi as the skin of Matha Sati fell on Mount Rudragiri on which the temple is situated. Anjanakshi means "Destroyer of Darkness," owing to two legends, one the burst of fire that happened when the mother's skin fell on the mountain; the other belief is that Matha Sati provided bright light from the sky to Brahma and Vishnu when they searched for a lost weapon in the area in the dark. Also, the Devas, the celestial deities, including Indra got cured of their illness by worshiping Shiva at this place and by the holy herbs obtained from the Mount Rudragiri on which Matha Satí's skin fell off and merged with Bhumadevi creating precious medicinal herbs. The present temple is situated on Rudragiri. The Devas were treated by Aswani Devata, the divine doctor at the behest of Shiva. Also, Lord Shiva appeared during a plague, during which the sage there was unable to make medicines for a lot of people. The Lord told people to eat a little of the mud of the holy Mount Rudragiri on which His consort Satí's skin merged, to get cured and this saved the people from the plague. Shiva henceforth obtained the name Marundeeswarar (Oushadheeshwar), Marundu literally means a Medicine. The temple has a recorded history from the 10th century, but scholar attribute the presence of the temple at least from the 8th century, pertaining to the period of Sundarar, the famous Saiva Nayanar. Sundarar has glorified the temple in his verses in 11th Thirumurai of Thevaram. The temple is counted as a twin temple along with Marundeeswarar Temple located in the same village.