Bala, an erstwhile assistant of Balu Mahendra wrote the script of Sethu in the mid-1990s and offered the film's lead role to his housemate Vignesh who refused the film.
The film was then titled Akhilam.JD Chakravarthy was then offered the lead role.JD Chakravarthy liked the script, but he was unable to sign the film as he was stuck in another project.The film was based on a real-life incident of a friend of Bala's, who had fallen in love, lost his mind and ended up at a mental asylum.Murali was then also considered for the lead role in the project, but did not sign up.In 1997, debutant director Bala offered Vikram the role of the rogue, Sethu (Chiyaan). The rest is history.Keerthi Reddy was initially signed on to play the lead female role, but was later replaced by Rajshri.Abitha later replaced Rajshri as Bala thought she could emote better.To prepare for the character, Vikram shaved his head, thinned down to half his size by losing 21 kilograms and grew nails for the role.Bala did not want Vikram to accept any other offers during this period to maintain the continuity of his looks and asked him to cease working as a dubbing artiste.The film's launch happened in April 1997 and production lasted close to two years as the film languished in development hell.The FEFSI strike of 1997 halted filming across the Tamil film industry from June to December 1997 and as a small budget film, Sethu was unable to progress during the period.When the strike was called off, the producer left the project and Vikram and Bala's assistant Ameer had to go and plead the producer to return, with filming resuming in January 1998.After further slow progress, the film was finally ready in June 1999.MS Bhaskar lent his voice for S. S. Raman who appeared as temple priest in this film.Rathnavelu who worked as a cameraman revealed that he gave the asylum scenes a predominantly green tone for the intense psychological impact.The film struggled to find a distributor and only after sixty-seven screenings did the film manage to find a buyer, with most refusing the film due to the tragic climax.During the period, Bala and Vikram used Vikram's wife Shailaja's money to organise press previews.Vikram has described the period of production as 'the worst phase of his career' as he was weak economically, and 'his fire was in danger of dying down'.Made on a shoestring budget, Sethu was a sleeper hit grossing almost 5 crore at the box office.The film initially began running at a single noon show at a suburban Chennai theatre but gradually built up audiences through word-of-mouth publicity and ran over 100 days at several cinema halls.The following year, Sethu won the National Film Award for Best Feature Film in Tamil, while also securing wins in the Best Film category at the Filmfare Awards and the Cinema Express Awards.The following year, Sethu won the National Film Award for Best Feature Film in Tamil, while also securing wins in the Best Film category at the Filmfare Awards and the Cinema Express AwardsBala won the Tamil Nadu State Film Award for Best Director and the Filmfare Award for Best Director – Tamil for his directorial debut.Owing to its success, the film was remade in Hindi as Tere Naam starring Salman Khan which became a success and also in Kannada as Huchcha which gave a major breakthrough to actor Sudeep.Jeevitha then remade the film in Telugu as Seshu with her husband Rajasekhar playing the lead.This film was also remade in Bangladesh as Tor Karone Beche Achi.Sethu started the trend of films with different themes that focused on realism and nativity.The scene where Vikram kidnaps and threatens Abitha to accept his love was imitated by Vadivelu in Style (2002)