The history of psychopharmacology is littered with type II errors--the rejection of effective compounds in the specious belief that they were inefficacious because they had failed to beat placebo in a controlled trial. Revisiting some of these drugs to establish their receptor profile, and then determining what patentable compounds now on the shelf match that profile, might represent a possible future pathway to drug discovery. This article looks at the special circumstances in which numerous potentially effective drugs were withdrawn in the United States.