Sodium thiopental (also called sodium pentothal (TM of Abbott Laboratories), thiopental (or thiopentone) sodium) is a short-acting barbiturate drug that induces brief general anesthesia (10-30 minutes) without analgesia by depression of CNS within 60 seconds of injection. Since analgesia is slight, thiopental is only used alone for brief procedures. It is more commonly used to induce hypnosis and anesthesia prior to the use of other anesthetic agents. It is also a radioprotective agent and used in narcotherapy. Along with pancuronium bromide and potassium chloride it is used in some States of the US as part of the lethal injection. In the past it was claimed as a truth drug.

Side effects include head ache, retrograde amnesia, emergence delirium, prolonged somnolence and nausea.

Its structural name is 5-ethyl-5-(1-methylbutyl)-2-thiobarbituric acid, empirically it is C11H17O2N2NaS.

It was discovered in 1936 by Ernest H. Volwiler and Donalee L. Tabern, working for Abbott Laboratories.