This article provides information on the use of methyl tertiary butyl ether (MTBE) as an octane enhancer in gasoline since the late 1970s. To assist water utilities and others in addressing instances of MTBE contamination, the US Environmental Protection Agency (USEPA) issued a health advisory for this chemical in December 1997. The details of the advisory are discussed here, as well as methods for MTBE removal. Includes 3 references.