Background and objective: The understanding, occasionally recognized, that Sigmund Freud had the intuition to use cocaine as local anesthetic for surgical procedures, or even that he played any role in the discovery of local anesthesia is not true. The objective of Freud's studies were different, and based in irrefutable evidence, Karl Köller was the real inventor of local anesthesia. In face of those facts, proper knowledge of this historically important subject is due.
Contents: This report refers to the long-known properties of cocaine. It also remembers personal data, and the professional and scientific activities of Sigmund Freud and Karl Köller. It presents Freud's researches on the pathophysiological effects of cocaine. It exposes the reasons for the harsh criticism of Freud's concepts. It describes the sudden, but conscious and justified, idea of Karl Köller to study scientifically the use of cocaine as a local anesthetic in animals and humans. It indicates how those pioneering studies, that culminated with the discovery of local anesthesia by Köller and two presentations in Vienna on the subject, were done. It also reports the first ophthalmologic surgery under local anesthesia. It shows the immediate dissemination throughout the world of the discovery that marked the beginning of regional blocks. It comments several documents corroborating the role of Köller in this discovery. And, finally, it mentions the numerous homages received by Köller in different areas of the world. COCLUSIONS: Regional block was introduced by Karl Köller in 1884, when he demonstrated the feasibility of performing painless ophthalmologic surgeries by using cocaine as a local anesthetic. Sigmund Freud studied cocaine extensively, but he did not have direct participation in this important discovery.