Okay people.
UFC tests their fighters so I doubt they juice, or at least just in the offseason, or just the undectables.
Pride doesn't test their fighters (Japan), I would say some of them do juice. Phil Baroni (the ney york badass) is fighting in Pride Fighting Champiionships now trying to resurect his career. He's won his last two fights solidly. I'd guess he may be back on the juice.