WEC 45: Cerrone vs. Ratcliff was a mixed martial arts event held by World Extreme Cagefighting that took place on December 19, 2009 at The Pearl at The Palms in Las Vegas.

[1] It marked the first time the WEC has held back-to-back events at The Pearl at The Palms.

[2] Damacio Page was originally slated to face Takeya Mizugaki at this event, but was pulled from the card and replaced by Scott Jorgensen.

[4] Debuting featherweights Brandon Visher and Tyler Toner were scheduled to face each other at this event, but Toner was removed from the event and replaced by fellow WEC newcomer Courtney Buck.

David Smith was supposed to make his WEC debut against John Hosman at this event, but was later pulled from the card due to injury and replaced by fellow WEC newcomer Chad George.