DNA viruses have evolved elaborate mechanisms to overcome host antiviral defences.In adenovirus-infected cells, programmed cell death (apoptosis) induced by the cytokine tumour necrosis factor (TNF) is inhibited by several adenovirus-encoded proteins [1-3]. Occupation of the cell-surface receptor Fas, a member of the TNF-receptor superfamily that is expressed on most cell types, triggers apoptosis of that cell [4-6]. Here we show that the adenovirus RID (for receptor internalization and degradation) protein complex, which is an inhibitor of TNF-induced apoptosis , mediates internalization of cell-surface Fas and its destruction inside lysosomes within the cell. Fas has not previously been shown to be internalized and then degraded. RID also mediates internalization of the receptor for epidermal growth factor [7,8], but it does not affect the transferrin receptor or class I antigens of the major histocompatibility complex. Removal of Fas from the surface of adenovirus-infected cells expressing RID may allow infected cells to resist Fas-mediated cell death and thus promote their survival.