Self-experimentation refers to scientific experimentation in which the experimenter conducts the experiment on themself. Often this means that the designer, operator, subject, analyst, and user or reporter of the experiment are all the same. Self-experimentation has a long and well-documented history in medicine which continues to the present. Some of these experiments have been very valuable and shed new and often unexpected insights into different areas of medicine.

There are many motivations for self-experiment. These include the wish to get results quickly and avoid the need for a formal organisational structure, to take the ethical stance of taking the same risk as volunteers, or just a desire to do good for humanity. Other ethical issues include whether a researcher should self-experiment because another volunteer would not get the same benefit as the researcher will get, and the question of whether informed consent of a volunteer can truly be given by those outside a research program.

A number of distinguished scientists have undertaken self-experimentation, including at least five Nobel laureates; in several cases, the prize was awarded for findings the self-experimentation made possible. Many experiments were dangerous; various people exposed themselves to pathogenic, toxic or radioactive materials. Some self-experimenters, like Jesse Lazear and Daniel Alcides Carrión, died in the course of their research. Notable examples of self-researchers occur in many fields; infectious disease (Jesse Lazear: yellow fever, Max von Pettenkofer: cholera), vaccine research and development (Daniel Zagury: AIDS, Tim Friede: Snakebite), cancer (Nicholas Senn, Jean-Louis-Marc Alibert), blood (Karl Landsteiner, William J. Harrington), and pharmacology (Albert Hofmann, and many many others). Research has not been limited to disease and drugs. John Stapp tested the limits of human deceleration, Humphry Davy breathed nitrous oxide, and Nicholas Senn pumped hydrogen into his gastrointestinal tract to test the utility of the method for diagnosing perforations.