Streptomyceticidal activity of Methyl tert-butyl ether (MTBE) elucidated for the first time. Adverse effect of MTBE, the gasoline additive, against 11 soil inhabitant Streptomyces spp. isolates was investigated. MTBE, an octane enhancer is added to gasoline to reduce atmospheric concentrations of carbon monoxide and ozone. It contaminates soil and groundwater by fuel leaks and spills. Streptomyces spp. are of the major contributors to the biological buffering of soils by exerting beneficial and antagonistic activity against wide range of bacteria and fungi. To evaluate anti-streptomycetidal activity of MTBE, it was tested against 11 soil isolates of Streptomyces isolates and also a plant-root bacterial pathogen, Erwinia carotovora and a plant-root fungal pathogen, Fusarium solani. MTBE did not reveal any growth inhibitory activity against E. carotovora and F. solani, but showed strong inhibitory effect against Streptomyces isolates. The Minimum Inhibitory Concentration (MIC) on Streptomyces isolates was 1/800 of the original MTBE. Fuel leaks and spills have the potential to suppress or eliminate the Streptomyces role in the soil causing alteration in the balance of soil micro flora. This change can promote the domination of microorganisms with adverse biological or ecotoxicological effects.