The film stars Kamal Haasan and Sridevi, while Y. G. Mahendran, Silk Smitha and Poornam Viswanathan played supporting roles.

It revolves around a school teacher who rescues a woman with retrograde amnesia, from a brothel, and protects her in his house located in Ketti.

Cheenu returns the next day and, after paying a huge sum to the madam, takes Vijaya out, supposedly on a pleasure trip.

From the doctor, Vedachalam learns that the person who had brought her there had been taking good care of their daughter; he withdraws his police complaint and they begin their journey to Madras with Viji.

[2] Silk Smitha, who had done around 20 films by then and was considered only for performing item numbers, was cast as the headmaster's sexually excited wife,[9] as Mahendra wanted a woman who was "sexy and at the same time a rustic beauty".

Poornam Viswanathan was initially reluctant to portray the headmaster as it deviated from the character roles he was then known for, but after convincing by Mahendra, agreed.

To shoot that scene, Mahendra sat on the steps of the train with a rope tied around his waist with crew holding and preventing him from falling down.

[2] Haasan refused to use a double, and strove to make Cheenu's injuries look real,[16] including giving the character a black eye and swollen lips.

Sexuality and the repression of desire are dominant motifs, similar to Balu Mahendra's previous film Moodu Pani (1980).

[22] When asked about the reason amnesia was chosen for a disability, Mahendra said the disorder is used as a camouflage and as an excuse to portray relationships in the film.

[23] Film critic Baradwaj Rangan finds the sequence where Cheenu narrates the story of the Blue Jackal to Viji to be a distant echo of the arc negotiated by Cheenu: "He is, after all, a nobody [like the jackal] who, through a salubrious twist of fate, becomes the ruler of a woman's life, until he is restored, at the end, to the nobody he was, a fraudulent claimant to her emotions.

[27] Nandini Ramnath, writing for the website Scroll.in, noted that Moondram Pirai contains elements common in Balu Mahendra's other films: "realism, evocative and naturalistic cinematography, strong performances, and psychosexual themes that drive the characters to make unusual and often tragic choices.

"[28] Hari Narayan of The Hindu said Cheenu "looks like a melange of [John] Keats' tragedy and [Sigmund] Freud's psychoanalysis."

Narayan explains the idea of Cheenu keeping Bhagyalaskhmi with him not only as an act of sympathy and love, but also with the intention to preserve her like a portrait.

Narayan also states that when Bhagyalakshmi recovers her memory and forgets him, Cheenu is hesitant to come back to his quiet existence, realising that in reality, dreams feel like its antithesis.

[32][33] The number "Kannae Kalaimane", which is based on the Kapi raga,[34] was written by Kannadasan in "about two minutes" time, after listening to the film's story and the situation for the song.

[2] The later picked up due to positive word-of-mouth, it became a "silver jubilee hit in many centres" and ran for more than a year in Subam theatre in Madras.

[2] According to Sathya Jyothi Films, Moondram Pirai received its highest distributor share in Madras and Coimbatore.

[49] Mid-Day's critic wrote that in Moondram Pirai, Mahendra "does not narrate a story in the traditional sense of the term.

He presents a whole fascinating array of vignetes and couches them in such endearing cinematic terms that it turns out to be a significant achievement not only for himself but also for the ethos he represents.

"[50] Kalki appreciated Moondram Pirai as a rare film where the lead actress was able to outshine Haasan in acting.

The critic also liked the way the story of the Blue Jackal was incorporated into the screenplay, appreciated Mahendra's cinematography, and concluded that the film was as perfect as a full moon.

[52] The magazine Aside gave a less favourable review, calling the film "a neon moon" and said, "There was at one time a brooding, premonitory quality about Balu Mahendra's movies ... but (he) has now gone into the trade of picture postcards and pani puri."

After a brief word of praise for Haasan's performance in the climax ("darkly luminescent, like a rain drenched monsoon night") the reviewer added, "Kamal makes a very amusing monkey, but should he not rather be playing a human character?

[16] Moondram Pirai attained cult status in Tamil cinema for its "unique amalgamation of high emotional quotient and film-making style".

[57] The climax scene where Haasan's character, Cheenu, runs after Sridevi's character, Bhagyalakshmi, who has recovered her memory but forgets the incidents that occur between her accident and recovery completely, and Cheenu trying desperately to make Bhagyalakshmi remember the time she spent with him, to no effect, became popular and was parodied many times.

[66] In February 2010, director R. Balki, in an interview with Forbes India, called Moondram Pirai as his favourite film.

[76] Balki mentioned in an April 2016 interview with Indo-Asian News Service, that Moondram Pirai "tremendously influenced" him as a filmmaker.

[11] Writer V. Vijayendra Prasad stated that he got the idea to write the story of the Telugu film Simhadri (2003) while watching Moondram Pirai.

[80] Mahendra described his 2003 directorial venture Julie Ganapathi as an inverse of Moondram Pirai as it was about "a mad woman who has a normal man in her house".