As the regulatory incentives to provide data on commercial chemicals increases, there will be greater opportunities to apply Quantitative Structure Activity Relationships (QSARs) and Structure Activity Relationships (SARs) to promote more efficient use of chemical testing resources. This paper summarizes the current applications of QSARs and SARs by the US Government organizations represented on the Toxic Substances Control Act Interagency Testing Committee (ITC) to predict aquatic toxicity, chemical or physical properties, environmental fate parameters and health effects of organic chemicals. The US Government organizations represented on the ITC that currently apply QSARs include the Agency for Toxic Substances and Disease Registry, the US Environmental Protection Agency (US EPA), and the Food and Drug Administration (FDA). The US Government organizations represented on the ITC that currently apply SARs include the US EPA, the FDA, the National Cancer Institute, the National Toxicology Program, and the National Institute for Occupational Safety and Health.