Rajadurgada Rahasya is a 1967 Indian Kannada-language film, jointly directed by A. C. Narasimha Murthy and S.K.Bhagwan and produced by A. Vasudeva Rao and T. Dwarakanath. The film stars Rajkumar, Bharathi, Udaykumar, Narasimharaju and Dinesh. The film has musical score by G. K. Venkatesh. Rajkumar plays dual roles in the movie. The movie was dubbed in Tamil as Malaikotai Marmam. This was the last movie where Bhagwan directed Bharathi Vishnuvardhan.
| Actor | Role |
|---|---|
 Dr. RajkumarRamanna Nayaka & Somanna Nayaka (Dual Role) | Ramanna Nayaka & Somanna Nayaka (Dual Role) |
 Bharathi VishnuvardhanNot listed | Not listed |
 DineshNot listed | Not listed |
 T. R. NarasimharajuNot listed | Not listed |
 Bangalore NageshNot listed | Not listed |
 UdaykumarNot listed | Not listed |