|UFC 31: Locked and Loaded|
|Promotion||Ultimate Fighting Championship|
|Date||May 4, 2001|
|Venue||Trump Taj Mahal|
|City||Atlantic City, New Jersey|
UFC 31: Locked and Loaded was a mixed martial arts event held by the Ultimate Fighting Championship at the Trump Taj Mahal in Atlantic City, New Jersey on May 4, 2001. The event was seen live on pay per view in the United States, and later released on home video.
The card was co-headlined by a Heavyweight title bout between Randy Couture and Pedro Rizzo, and a Welterweight Title Bout between Pat Miletich and Carlos Newton. The card also featured the first appearance of former Lightweight and Welterweight champion BJ Penn, former Welterweight Champion Matt Serra, and Kevin Randleman's first fight at 205.
UFC 31 again saw reformed weight classes, adopting the current standard. Bantamweight was renamed Lightweight and raised from 150 to 155. Welterweights were now at 170, Middleweights at 185, and Light Heavyweights at 205.