Rafael Guimarães dos Santos is a tenured professor (Professor Doutor) in the Psychiatry Division of the Ribeirão Preto Medical School at the University of São Paulo (FMRP-USP), Brazil. He is a researcher at the National Institute of Science and Technology for Translational Medicine and coordinates the Phantastica Lab (Laboratory of Studies with Psychedelic Hallucinogens in Mental Health).

Over the past 20 years, he has conducted clinical research on the effects of ayahuasca in healthy volunteers and in patients with social anxiety, post-traumatic stress, cancer-related depression, and treatment-resistant depression. In 2025, he was recognized by a Stanford University survey as being among the world’s top 2% most-cited scientists. He has been a member of the ICEERS Advisory Board since 2012.