Psychiatric research with hallucinogens has resumed in the U.S. after two decades of virtual prohibition. Formal authorization from United States regulatory agencies to conduct investigative studies in humans with hallucinogens has been successfully obtained. However, the resumption of psychiatric research with halluci- nogens in the U.S. is proceeding very cautiously. The projects now underway are Phase I studies, meaning they are conducted in non-clinical populations to establish basic dose-response and safety parameters. In July 1992, both the National Institute of Drug Abuse (NIDA) and the Food and Drug Administration (FDA) held meetings in Washington, D.C. to examine the topic of human experimentation with hallucinogens. These meetings of scientists and health policy makers determined that drugs classified as hallucinogens, although possessing an inherent abuse potential, do have a safety profile of acceptable magnitude when compared to drugs currently the subject of formal research investigation, as well as others actively dispensed in clinical practice. Thus, the FDA stated that formal and well-controlled investigations designed to assess the risk-benefit ratio of particular hallucinogenic substances may now be pursued (DOBLIN1993). These basic studies are to assess the safety and the physiological and psychological effects of dimethyltryptamine (DMT), 3,4-methylenedioxymethamphetamine (MDMA) and ibogaine. Sanction to conduct human research with such drugs, however, stipulates that volunteers for these studies must have had prior first-hand expe- rience with the drug under investigation, as there is still concern that administering potential substances of abuse to as yet unexposed brains could create ethical and liability dilemmas. In effect, the FDA has approv- ed human research with a variety of hallucinogens, but has stated explicitly that they must be treated in a manner similar to other conventional drugs which have been submitted for FDA approval. Thus, research into the clinical efficacy of hallucinogens, although allowed to emerge after a quarter-century of dormancy in the United States, may proceed now only at a very slow pace. In order to learn from the mistakes of the past and to apply these lessons for the future guidance of human research with hallucinogens, this paper reviews the history of the Western political and medical repression of hallucinogens. The recently initiated contemporary studies of hallucinogens are reviewed to illustrate the developments in these areas.