Depends on what you deleted them from, how long it's been and if any writing has been done to the media since.
Like for instance, if you want to recover pics from a camera's memory card and you haven't taken any pictures since, it's very likely that you'll get all or most of your pics back. But if it's on the hard drive of your pc, good luck with even getting any back. If it hasn't been that long and you haven't installed anything you might get lucky and get a few back.
I recently recoverd some pictures from my boss' digital camera that were accidentally deleted using Active Undelete, it costs money but it works great.