American physicians markedly undertreat severe pain based on an irrational and undocumented fear that appropriate use will lead patients to become addicts. Such irrational fear-opiophobia-resists educational intervention as phobic fears resist rational explanation and exploration. Because this phobia has become fixed in the customary behavior of physicians, it is particularly resistant to change. Re-education might better be directed to the changing of mistaken attitudes about drug use and abuse that are part of the American culture and which are not amenable to alteration by medical education.