In 1956, Dr. Robert Galbraith Heath, Chair of Psychiatry and Neurology at Tulane University School of Medicine in New Orleans, announced that he and colleagues had discovered a protein they called taraxein in the blood of schizophrenic patients that caused symptoms of schizophrenia when injected into healthy volunteers. Heath's claim received wide public and professional attention. Researchers quickly tried to confirm the discovery. These efforts, which were rigorous and in some cases conducted in consultation with the Tulane researchers, failed. Nevertheless, for the next four decades Heath continued to defend his claim. This article recounts the scientific developments that led up to Heath's putative discovery and it explores the scientific findings for and against the taraxein theory of schizophrenia.