A psychedelic drink used for centuries in healing ceremonies is now attracting the attention of biomedical scientists as a possible treatment for depression. Researchers from Brazil last month published results from the first clinical test of a potential therapeutic benefit for ayahuasca, a South American plant-based brew. The work forms part of a renaissance in studying the potential therapeutic benefits of psychedelic or recreational drugs - research that was largely banned or restricted worldwide half a century ago. Ketamine, which is used medically as an anaesthetic, has shown promise as a fast-acting antidepressant; psilocybin, a hallucinogen found in 'magic mushrooms', can help to alleviate anxiety in patients with advanced-stage cancer; MDMA (ecstasy) can alleviate post-traumatic stress disorder; and patients who experience debilitating cluster headaches have reported that LSD eases their symptoms. Ayahuasca, a sacramental drink traditionally brewed from the bark of a jungle vine (Banisteriopsis caapi) and the leaves of a shrub (Psychotria viridis) ... has been studied by anthropologists, social scientists and theologians, but clinical research on ayahuasca has been limited to observation of its effects in mice and rats, and in healthy human volunteers, including brain-imaging studies and retrospective surveys of past use. Further trials are under way.