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 headlined by a heavyweight title bout between Randy Couture and Pedro Rizzo.

A welterweight title bout between Pat Miletich and Carlos Newton also occurred.

UFC 31 again saw reformed weight classes, adopting the current standard under the new Unified Rules of Mixed Martial Arts, set by the New Jersey State Athletic Control Board a month earlier in April 2001.