Enhanced in situ anaerobic bioremediation of chlorinated solvents is a cost-effective, expanding technology for the clean-up of chlorinated solvent-contaminated sites. However, this technology is knowledge-intensive and its application requires a thorough understanding of the microbiology, ecology, hydrology and geochemistry of chlorinated solvent-contaminated aquifers. This review summarises current knowledge and future perspectives in the area of microbial anaerobic dechlorination of chlorinated solvents, particularly chloroethenes. Main attention is paid to the discussion of environmental factors and conditions that influence microbial activity under field conditions. Approaches to stimulate and manipulate the activity of native dechlorinating populations in order to meet target remediation goals for both plume management and source treatment are reviewed in detail. Possible research efforts needed to increase the likelihood of success of this technology are finally presented. (c) 2006 Society of Chemical Industry.