Public concern about environmental and health effects from the disposal of residues from the manufacture of agricultural and industrial process chemicals into landfills led to the passage of the Comprehensive Environmental Response, Compensation and Liability Act of 1980, commonly referred to as the 'Superfund' Law. One method of defining the potential toxicity of these chemical residues is the use of bioassays, a number of which use bacteria as the test organism and have been proposed to assess the impact of chemical pollutants on the environment. Efforts were directed toward the establishment of short-term methods that are inexpensive, rapid, reproducible and sensitive. A major advantage of microbial toxicity tests over chemical analysis is their direct assessment of potential biotic impact without extrapolation from chemical analysis of uncertain completeness. It was the intent of the paper is to evaluate the relative sensitivity, precision, and accuracy of three published microbial bioassay procedures for ascertaining their ability to define the toxicity potential at hazardous waste sites.