In horse racing, maiden races are contests in which none of the horses in the field have ever won.
Maiden contests are divided into various levels that usually indicate how much promise the owner and trainer believe the horse possesses.
If the horse seems like it could develop into a stakes winner, they will likely start it out in a maiden special weight race, where the horse cannot be claimed or purchased by a rival owner.
If the horse appears to be talented but not quite a stakes-caliber runner, they might decide to enter it in a high-level maiden claiming race. If they go this route and enter the horse in a $50,0000 maiden claiming race, for example, they risk losing the horse but know they will at least get a $50,000 return on their investment if they do.
Sometimes they will conclude that a horse just isn’t very fast or can’t absorb the lessons they have tried to impart. In that case, they may enter it in a low-level claiming race where they could lose it for as little as $8,000 (or even less at smaller tracks).