Thappu Thalangal was directed by K. Balachander and produced by KB close associates banner Premalaya which released in 2 languages Tamil and Kannada.  The Kannada version (Thappida Thala) released before the release of Tamil Version.  Thappida Thala was released on 06.10.1978 and Thappu Thalangal was released for 1978 Deepavali (30.10.1978). Two more Rajini films were released together with Thappu Thalangal and they are Thaai Meethu Sathyam and Aval Appadithaan.

Following movies were released on the same day :

Pilot Premnath - Sivaji Ganesan - A.C. Thrilokchandar
Sigappu Rojakkal - Kamal Hassan - Bharathiraja
Manitharil Ithanai Nirangala - Kamal Hassan - R.C. Shakthi
Kanna Moochi - Sivakumar - R. Pattabiraman
Vandikaran Magan - Jaishankar - Amirtham
Athistakaran - Nagesh - Venu
Thanga Rangan - Thengai Srinivasan - Dakshnamoorthy

At Chennai, Thappu Thalangal was released at Pilot, Broadway, Krishnaveni and Uma as a regular shows at all theaters.
 
This was a black and white film which was produced in very low budget.  Inspite of big films (those days) like Pilot Premnath, Sigappu Rojakkal, Thai Meethu Sathyam, Vandikaran Magan, etc Thappu Thalangal did a decent business and commercially became a hit.

During those days, this film opened with reservation in all the city theaters and it is not easy to pull the audience to the theaters for one film but imagine our Superstar had created waves and broken that record that he can pull the audiences to all his 3 films at a time.

In Thappu Thalangal, the major plus point was KB dialogue and daring attempt in the film industry after Arangkettram.

Rajini with a  big mustache was a big attraction at the Pilot theatre stills board. Kamal only plays a minuscule guest role but he had a good coverage in the stills. People were trying to assume the story of the movie looking at the stills, with some people saying, Kamal is the hero, he and Sarita are happy going couple and Rajini disturbs their life and he is the villain etc. Ultimately every one got it wrong, Rajini was the hero of the film.

This film received well critically, with people appreciating the acting of Rajini. "Ennada Polladha Vazhkai" song was a rage that time, with radio playing the song very frequently. Rajini's acting in the climax scene was a revelation and Tamil cinema had not seen such type of emotions from any actor for an action packed emotional climax. Rajini would have just killed the villan (Sundar - Kannda Actor), and will be returning with a satisfying and yet regretful emotion, only to meet his sister who will tell him that, she is now happy and she has just married to the villan with out realizing that Rajini has killed him. That emotions which he displays in the climax left the viewers spell bound. Rajini will display  mix of loud laughter, cries, anger, anguish, disgust, disappointment, all in one shot in that scene. Rajini’s character "Devu" became famous those days!

According to the box office performances, Thappu Thalangal ran more than 75 days in all the major cities and distributors share was very profitable and motivated them to buy forthcoming Rajini movies. 

One of the leading producer Panchu Arunachalam explained about the black and white low budget movie releases.  During 60 & 70’s, it will not cost more than 6 to 7 lakhs to produce a film for upcoming actors.  If they release the film with 25 prints, definitely they will earn around 25 to 30 lakhs for a good film and this will be considered as a great business those days.  This is the scenario for our Thappu Thalangal. 
 
Number of days Thappu Thalangal managed to run in the city areas as follows:

Madurai - Sivam - 89 Days in 3 shows (highest run)
Coimbatore – Arul – 75 Days 3 shows
Salem – Theater name unknown - 75 Days in 3 shows
Chennai - Pilot - 74 Days in 3 shows
Chennai - Broadway - 75 Days in 3 shows
Chennai - Krishnaveni – 68 Days in 3 shows
Chennai - Uma – 68 Days in 3 shows
Trichy – Theater Name Unknown - 61 Days 3 shows
Vellore – Raja – 40 Days in 3 shows

During the time of Thalapathy release, Bangalore fans released a special sovegnier (Malar) on our Superstar and it mentioned that Thappu Thalangal ran 100 days in Kovai - Arul Theater . Can someone confirm this news?

- T.Ve. Rajesh & Dharma