This report provides a basic orientation and current status of bioremediation for contaminants located in the subsurface. This report contains information gathered from a range of currently available sources, including project documents, reports, periodicals, Internet searches, and personal communication with involved parties. References for each case study are provided immediately following the case study. All sources are organized in alphabetical order at the end of the document. No attempts were made to independently confirm the resources used. It has been reproduced to help provide federal agencies, states, consulting engineering firms, private industries, and technology developers with information on the current status of this project. This paper addresses the status of the application of biological treatment to clean up hazardous metals from the earths subsurface (i.e., in situ bioremediation). The target audience includes federal and state regulators, planners, and site managers.