Kadhalar Dhinam ( transl. Lovers Day) is a 1999 Indian Tamil-language romance film written and directed by Kathir. The film stars Kunal and Sonali Bendre in the lead roles, while Nassar, Manivannan, Goundamani and Chinni Jayanth appear in supporting roles. It is based on a love relationship which begins through an internet chatroom and takes a turn after the protagonist has second thoughts about the relationship after finding out his lover's true identity.

Kadhalar Dhinam is the debut film for Kunal and the first Tamil film for Bendre. The film, produced by A. M. Rathnam, had music composed by A. R. Rahman, cinematography by P. C. Sreeram and editing by B. Lenin and V. T. Vijayan. It was released on 9 July 1999, while a partially reshot but mostly dubbed Hindi version, Dil Hi Dil Mein was released on 21 April 2000. The film received positive reviews and was a commercial success. It was also dubbed in Telugu as Premikula Roju.