A review on metabolism and toxicity of the fluorinated anesthetic agent, fluroxene, is presented. Fluroxene anesthesia is nontoxic to man but fatal to many experimental animals. The fluroxene molecule (2,2,2-trifluroethyl vinyl ether) is composed of two moieties; both are toxic as a result of their metabolism: the vinyl moiety destroys heme of cytochrome P-450 while being metabolized to the final product, CO2. The trifluoroethyl moiety is oxidized to trifluoroethanol (TFE) and trifluoroacetic acid (TFAA), and the acute toxicity of fluroxene is related to this pathway. The ratio of metabolities (TFAA to TFE) excreted by different species exposed to fluroxene varies; whenever highly toxic TFE is the major metabolite, fluroxene toxicity is high (rodents, dogs, phenobarbital pretreated monkeys), whenever TFAA is the major metabolite (man, monkey) fluroxene is not toxic. Toxicity in different species also correlates with the extent of glutathione depletion following fluroxene exposure. Fluroxene metabolism and toxicity are modified by drugs metabolized by or affecting the activity of the microsomal cytochrome P-450-system or enzymes involved in ethanol metabolism. The susceptibility of fluroxene to two enzymatic systems which are modified by environmental and genetic factors may explain the large differences in fluroxene toxicity to various species. The fate of one-third of fluroxene administered to man remains unknown.