ATP binding cassette (ABC) transporters define a family of proteins with strong structural similarities conserved across evolution and devoted to the translocation of a variety of substrates across cell membranes. A few members of the family are known in mammals, but although all of them are medically relevant proteins, knowledge of their molecular function remains scanty. We report here a morphological and functional study of the recently identified mammalian ABC transporter, ABC1. Its expression during embryonic development correlates spatially and temporally with the areas of programmed cell death. More specifically, ABC1 is expressed in macrophages engaged in the engulfment and clearance of dead cells. Moreover, ABC1 transporter is required for engulfment since the ability of macrophages to ingest apoptotic bodies is severely impaired after antibody-mediated steric blockade of ABC1. A structural homologue of ABC1 has been identified in the Caenorhabditis elegans genome and maps close to the ced-7 locus. Since ced-7 phenotype is precisely defined by an imparied engulfment of cell corpses, it is tempting to surmise that ABC1 might be a mammalian homologue of ced-7.