During cell death, nuclear material is released into the cellular environment and into the circulation. Studies in experimental animals have shown that circulating DNA is rapidly removed by the liver and broken down to oligonucleotides. The authors have used a perfused liver system in the mouse to study hepatic binding of single-stranded DNA. DNA binding to the liver was rapid and efficient, and did not require serum factors. Binding was saturable and temperature independent, suggesting a receptor-mediated process. Electron microscope autoradiography demonstrated DNA binding to sinusoidal lining cells, primarily Kupffer cells. In vitro studies with isolated cells confirmed that DNA bound to a trypsin-sensitive receptor on the adherent subset of hepatic nonparenchymal cells. The integrity of the perfused liver was confirmed by the demonstration of appropriate uptake and breakdown of asialoorosomucoid. Despite rapid binding of DNA, however, the perfused liver did not digest DNA or release DNA breakdown products. Infusion of DNAse at intervals after DNA perfusion demonstrated that significant amounts of DNA remained bound to the cell surface, and that serum nucleases were able to cleave this surface bound DNA. It is concluded that DNA binding to the liver is mediated by a receptor on Kupffer cells, but that DNA breakdown may occur at the cell surface or in circulation and may not require cell interiorization.