The use of microorganisms to destroy, or reduce the concentration of, hazardous wastes on a contaminated site is called bioremediation. Such a biological treatment system has various applications, including, clean up of contaminated sites such as water, soils, sludges, and waste streams. The treatment of the Alaskan shoreline of Prince Williams Sound after the oil spill of Exxon Valdez in 1989 is one common example in which bioremediation methods got public attention. There are numerous other success stories of bioremediation in cleaning up chemical spills, leaking underground storage tanks of gasoline, and many toxic industrial effluents. This paper outlines the various factors, including scientific, non-scientific, and regulatory, that limit the use of bioremediation technologies.