Infernal Affairs II is a 2003 Hong Kong crime-thriller film directed by Andrew Lau and Alan Mak.

It is a prequel to the 2002 film Infernal Affairs. Anthony Wong, Eric Tsang, Edison Chen, Shawn Yue, and Chapman To reprise their roles from the original film alongside new cast members Carina Lau, Francis Ng, Roy Cheung and Hu Jun. Both Tony Leung and Andy Lau, who played the central roles in the original, do not appear in the film, as they are replaced by the younger versions played by Yue and Chen, respectively. The events of the film take place from 1991 to 1997.

The film opens in 1991, 11 years before the events of Infernal Affairs. Inspector Wong Chi-shing is discussing the death of his first partner with Hon Sam, the triad boss in the first film. At this point, Hon is a member of Ngai Kwun's triad family, and is also working as Wong's informant. Carrying a nondescript paper bag, a young Lau Kin-ming makes his way through the streets of Mongkok before stopping at an ostensible martial arts school, where he kills Ngai Kwun with a gun concealed in the bag and walks away.