Arinthum Ariyamalum (transl. Knowingly and Unknowingly) is a 2005 Indian Tamil-language crime action film written and directed by Vishnuvardhan. It stars Navdeep, Prakash Raj, and newcomers Arya and Sameksha, while Adithya, Sangili Murugan, Krishna, and Yog Japee play pivotal roles. The film's music was composed by Yuvan Shankar Raja. "Punnagai Poo" Gheetha, a RJ at a Malaysian radio station THR Raaga, produced the film.

The film was released theatrically on 20 May 2005. It completed a 175-day run at the box office. The film eventually went on to receive Filmfare Award for Best Male Debut – South for Arya. It was remade in Odia as Prema Rutu Asilare in 2006. In 2015, the film was released on Blu-ray in the UK.