S&M can be an abbreviation for:

• Sadism and Masochism (AKA sadomasochism), a form of Sexual roleplaying.
• San Francisco Symphony and Metallica, a Metallica concert and the album of said concert.
• Sign & Magnitude, a means to encode signed integers in binary.
• A British comedy show starring Tony Slattery and Mike McShane.
• Shorthand term for the country of Serbia and Montenegro.