Mouna Ragam ( transl. Silent Symphony) is a 1986 Indian Tamil-language romantic drama film written and directed by Mani Ratnam, and produced by G. Venkateswaran. The film stars Mohan and Revathi, with Karthik in a guest appearance. V. K. Ramasamy, Ra. Sankaran, Bhaskar, Kanchana, Vani, Kalaiselvi and Sonia play supporting roles. It narrates the life of Divya (Revathi), a free-spirited college girl who is forced into an arranged marriage with Chandrakumar (Mohan) by her father (Sankaran) though she still lives with the memory of her deceased lover Manohar (Karthik). The story follows Divya's inner conflict between holding on to her past and coming to terms with the present.

The film's development began when Ratnam began writing a short story titled "Divya" with no cinematic plans until he finished it. Since production on his directorial debut Pallavi Anu Pallavi (1983) was delayed, he took a break for a month and developed "Divya" into a film script, which would eventually be renamed Mouna Ragam. Although Ratnam began work on the script during Pallavi Anu Pallavi, it languished in development hell and ended up becoming his fifth film. Mouna Ragam was the first film produced by Venkateswaran's Sujatha Films, and was shot primarily in Madras, with additional filming taking place in Delhi and Agra. The music was composed by Ilaiyaraaja, with lyrics by Vaali. P. C. Sreeram was the cinematographer, and the art director was Thota Tharani. The film was edited by B. Lenin and V. T. Vijayan.

Mouna Ragam was released on 15 August 1986. Despite opening to modest audiences, it became a box-office success, with a theatrical run of over 175 days, and Mani Ratnam's breakthrough. The film received critical acclaim; it won the National Film Award for Best Feature Film in Tamil, and Ratnam received the Filmfare and Cinema Express Awards for Best Director in Tamil. Mouna Ragam also became a breakthrough in Karthik's career despite his role being a cameo. The film introduced techniques such as soft-focus shots, flare filters and backlighting, which became popular in Tamil cinema. It was remade in Hindi in 1992 as Kasak, and in Kannada in 1999 as Chandrodaya.