Oru Vidukadhai Oru Thodarkadhai () or () is a 1979 Indian Tamil-language film directed by M. A. Kaja. The film was remade in Malayalam as Oru Thira Pinneyum Thira.
Thyagarajan and Kamala are in love but are separated due to unforeseen events in their lives. Kamala has moved to New Delhi and is married off to a philandering husband who has no affection for her.
Years later, Thyagarajan joins an office in a managerial role and, to his surprise, finds that Kamala works under him. As time rolls Kamala learns that Thyagarajan's wife, a sports fan, has deserted him for his close friend Bhaskar, a basketball player.
The erstwhile lovers unhappy in their personal lives become supportive of each other. The rest of the story unveils whether Kamala and Thyagarajan find happiness in their lives or remain unhappy.
The soundtrack was composed by Gangai Amaran making his debut as composer with this film. Amaran revealed his debut film as composer Malargalile Oru Malligai was unreleased despite the soundtrack being released, so Oru Vidukathai Oru Thodarkathai became his first film as composer to be released. All songs were written by Vaali and Amaran. The songs "Nayagan Avan Puram" and "Vidukathai Ondru" became hugely popular.
Kausikan of Kalki gave a negative review citing director Kaja's audacity is frowned upon and he should not continue with this kind of stories.