Midhunam movie is all about Sethumadhavan (Mohanlal) who has plans to start a biscuit factory near his house. But the bureaucracy and the corruption of the officials are the hurdles in front of him. Along with that he has to solve the problems in his family, which his brother (Innocent) and brother-in-law (Jagathy Sreekumar) creates. he marries his long-term fiancée Sulochana (Urvashi) who always cribs that he doesn't have love towards her, which he had shown before their marriage. How sethumadhavan succeeds in his life beating all the odds against him forms the rest of the story.
| Actor | Role |
|---|---|
 MohanlalSethumadhavan | Sethumadhavan |
 UrvashiSulochana | Sulochana |
 SreenivasanPreman | Preman |
 Thikkurissy Sukumaran NairKurup Master | Kurup Master |
 SukumariSwamini Amma | Swamini Amma |
 InnocentKurup | Kurup |
 Jagathy SreekumarSuguthan | Suguthan |
 JanardhananSivaraman | Sivaraman |
 ZeenathNot listed | Not listed |
 SankaradiSethu's Maternal Uncle | Sethu's Maternal Uncle |
 C I PaulChief Engineer Karunakaran | Chief Engineer Karunakaran |
 Kuthiravattam PappuPeethambaran | Peethambaran |
 Nedumudi VenuChekkodu Swamy | Chekkodu Swamy |
 MeenaNot listed | Not listed |
 KaveriSulochana's Younger Sister | Sulochana's Younger Sister |
 KanakalathaSivaraman's Wife | Sivaraman's Wife |
 UshaShyama | Shyama |
 NandhuNot listed | Not listed |
 James ChackoPappi | Pappi |
| VVishal MenonRajesh | Rajesh |
 Kuttyedathi VilasiniShyama's Kunjamma | Shyama's Kunjamma |
 Kozhikode Narayanan NairVillage Officer | Village Officer |