| Release Date | 12 December 2002 |
| Other Names | Infernal Affairs |
| Tagline | Loyalty. Honor. Betrayal. |
| Genre | Crime, Drama, Romance, Thriller |
| Country | Hong Kong |
| Language | Cantonese, English, Thai |
| Sound Mix | Dolby Digital |
| Color | Black and White, Color |
| Film Type | Feature |
| Film Class | Gangster Film, Police Drama |
| Mood | Tough Guys |
| Themes | Faltering Friendships, Police Corruption, Going Undercover, Triad, Double Life |
| Tones | Menacing, Stylized, Confrontational, Slick, Gritty, Tense |
| Tags | Classmate, Identity, Organized Crime, Police Academy, Police Chief, Speech, Undercover |
Infernal Affairs is a 2002 Hong Kong crime-thriller film directed by Andrew Lau and Alan Mak. It tells the story of a police officer who infiltrates the triads, and a police officer secretly working for the same gang. The Chinese title means "the non-stop path", a reference to Avici, the lowest level of hell in Buddhism. The English title is a word play combining the law enforcement term "internal affairs" with the adjective infernal. Due to its commercial and critical success, Infernal Affairs was followed by a prequel, Infernal Affairs II, and a sequel, Infernal Affairs III, both released in 2003, as well as a 2006 American remake, The Departed.