[1] She is worshipped mainly in Bihar, Odisha, Bengal, Jharkhand, South Assam and other parts of northeastern India and in Uttarakhand, chiefly for the prevention and cure of snakebite, and also for fertility and prosperity.

In Hinduism, Manasa is the sister of Shesha and Vasuki, king of Nāgas (serpents), and wife of sage Jaratkaru.

[4] Denied full godhood due to her mixed parentage, Manasa's aim was to fully establish her authority as a goddess, and to acquire steadfast human devotees.

[5] Bhattacharya and Sen suggest that Manasa originated in South India as a non-Vedic and non-Aryan goddess and is related to the Kannada folk snake-goddess Manchamma.

[9] According to Tate, Manasa as Jaratkaru was initially recognized as a daughter of the sage Kashyapa and Kadru, the mother of all nagas in the epic Mahabharata.

[12] By the 14th century, Manasa was identified as the goddess of fertility and marriage rites and was assimilated into the Shaiva pantheon, related to the god Shiva.

As a consequence, stories attributing Manasa's birth to Shiva emerged and ultimately Shaivism adopted this indigenous goddess into the Brahmanical tradition of mainstream Hinduism.

[11] Alternatively, Vasudev suggests that the Bengali tale of Manasa reflects rivalry between Shaivism and the goddess-centric Shaktism.

Astika also helped in saving the naga race from destruction when King Janamejaya decided to exterminate them by sacrificing them in his yajna, called the sarpa satra.

Upon being pleased, Krishna granted her divine Siddhi powers and ritually worshipped her, making her an established goddess.

Vasuki accepted Manasa as his sister, and granted her the charge of poison that was produced when King Prithu milked the Earth as a cow.

She was initially mocked by the people but then Manasa forced them to worship her by raining calamity on those who denied her power.

Manasa killed him but Behula floated on water for nine months with the dead body of her husband and finally brought back the lives of the seven sons and the lost prosperity of Chand.

This gesture made Manasa so happy that she resurrected all of Chand's sons and restored his fame and fortunes.

[22] Ananda K. Coomaraswamy and Sister Nivedita say, "[The] legend of [Chand Sadagar and] Manasā Devī, [...] who must be as old as the Mykenean stratum in Asiatic society, reflects the conflict between the religion of Shiva and that of female local deities in Bengal.

The following of Manasa is most widespread in South Bengal, where she is ritually worshipped in the local temples as well as in the houses.

Manasa is also a very important fertility deity, especially among the lower caste Hindus, and her blessings are invoked during marriage or for childlessness.

In North Bengal, among the Rajbanshis, Manasa (called Bishohora, Bishohori or Padmavati) is one of the most important goddesses, and her thaan (shrine) may be found in the courtyard of almost every agrarian household.

Several artefacts and sculptures found in and around the place made locals believed that it was where Chand Saudagar had his Rajbari.

[26] Every year, from 16 to 19 August, Bhagalpur springs up like a scented flower to worship the local guardian Manasa and commemorate the wedding of Behula[27] Manasa is also worshipped extensively in Assam and Tripura, and a kind of Oja-Pali (musical folk theatre) is dedicated entirely to her myth.

Bengali women observe a fast (vrata) on this day and offer milk at snake holes.