Methyl tertiary-butyl ether(MTBE) is used as an octane enhancer in gasoline. MTBE can enter the environment at any stage in the production, storage, and transport of undiluted MTBE or MTBE-blended gasoline. Although data on concentrations of MTBE in the environment are not available, modelling of fate of MTBE has provided predictions for concentrations of MTBE in the various media to which humans and other organisms may be exposed. Many individuals do not taste or smell MTBE at the $5{mu}g/L$ level, and thus may be exposed to higher concentrations for a significant amount of time. MTBE exposure through inhalation is likely to be below health-threatening levels, except for occupational workers such as gasoline station attendants and auto mechanics. It should be stressed, however, that there are important data gaps in our understanding of the acute and chronic toxicity of MTBE. Little or no research concern including being conducted that directly addresses these issues. Rather than any immediate ban on MTBE, I recommend consideration of phasing out MTBE in USA and other countries. During the transition phase, a number of policies are suggested to reduce the risk of using MTBE. One of these policies is that the state should invest in a research program. Such research should, for example, examine effective alternatives for motor vehicle fuels, and detect concentrations of MTBE in ambient air, water, and other environmental media.