Halothane vapour is an inhalational general anaesthetic. Its systematic name is 2-Bromo-2-chloro-1,1,1-trifluoroethane.

This halogenated hydrocarbon was first synthesized by Suckling of ICI in 1951. Once widely used as general anaesthetic, it has largely been replaced by sevoflurane and desflurane for human use. Halothane is still widely used in veterinary surgery and the third world because of its lower cost.

Halothane rarely shows any ill effects when used once on a patient. After multiple exposures to halothane, however, the risk of developing severe liver damage increases. This is because a small fraction of the vapour is metabolised to neoantigens. On rare occasions, this triggers a fatal autoimmune reaction, "halothane hepatitis ". Descendants of flurane , enflurane and isoflurane, were developed largely with the aim to find anaesthetic vapours that do not metabolise.

The halothane test is used for determining stress susceptibility for genetic selection programs.