Security Unlimited (Chinese: 摩登保鑣) is a 1981 Hong Kong comedy film directed by and starring Michael Hui and co-starring his brothers Samuel Hui and Ricky Hui, who are known as the Hui Brothers. Michael Hui was awarded Best Actor at the 1st Hong Kong Film Awards, making him the first ever recipient for the award.

Chow Sai-cheung (Michael Hui), a bitter supervisor of a Hong Kong private security company, teaches unusual guard tactics to new recruits such as electric mats, parachuting off burning buildings and counter-attacking gunfire. He was secretly observed by his new boss (Stanley Fung) and Sylvester (Arnis Hasi), unimpressed by his work, the new boss demotes Chow and promotes Chow's assistant Sam (Samuel Hui). Under the leadership of Sam, Chow and new recruit Bruce Tang (Ricky Hui) encounter a slew of misadventures, including pursuing stowaways on a party boat. Bruce ultimately falls in love with one of the stowaways. Finally, they all get entangled in a plot to steal one of China's most prized treasures on display in Hong Kong, and in a plot involving some missing government money that the security officers were guarding.

The film was the biggest grossing of the Hui Brothers comedies and became the biggest grossing film of all-time in Hong Kong with HK$18 million.^[1] It also became the highest-grossing film of all-time in Singapore with a gross of S$1.4 million.^[2]

Security Unlimited is Samuel Hui's eighth Cantopop album with the title track being the film's theme song.