FACT: If you are allowed to submit opening pages along with your email query pitch letter, including the prologue pages will kill your query 99.9% of the time and agents won’t ask for sample pages.
Most writers use the prologue for the wrong purpose.
* Prologues are written in a different narrative voice than the rest of the novel so do not represent an accurate sample of the writer’s voice for the story. (And usually the voice in prologues are the easy-to-do-poorly distant omniscient third person POV).
* Prologues given are usually the back story for the novel and writers use it as a “crutch” to get started. If you are a writer at the top of your game, you won’t need it.
* Prologues are used as world-building so the reader can understand the world before diving into the story. Once again, if you are a writer at the top of your game, you won’t need it. You’ll build in the world within your opening chapter.
I’ve blogged ad nauseum about this topic so check the side bar archives on “passing on sample pages” and “beginning writer mistakes” for more in-depth details.