DNA filter elution assays have proved useful in studies of DNA strand breaks and crosslinks produced in mammalian cells or tissues by a wide variety of carcinogenic and cancer chemotherapeutic agents. The basic types of DNA lesions that can be measured include single and double-strand breaks, interstrand crosslinks and DNA-protein crosslinks. DNA filter elution has also been adapted to the assay of other lesions such as alkali-labile sites and the protein-associated strand breaks of topoisomerase DNA cleavage complexes. The essential concepts and theory of the technique are discussed and the applications of the technique to various types of studies are critically reviewed.