Short-term tests have been developed to serve as rapid and relatively inexpensive predictors of a chemical's potential to cause chronic effects. These tests employ bacteria, yeast, plants, insects, isolated mammalian cells and whole animals. Short-term tests can detecta chemical's genotoxicity, that is, its ability to alter a cell's genetic material (DNA). The document is organized into five sections. The first section discusses how short-term tests can contribute to hazard assessment, while the second describes the scientific basis and techniques of short-term tests. A general strategy for how short-term tests can be used to detect a chemical's potential long-term toxicity is outlined in the third section. Some program applications of short-term test research are presented in the fourth section, and the fifth section describes some of the current research activities. An overall perspective concludes the document. A glossary of technical terms is provided at the end of the document along with an appendix of technical information on specific short-term tests.