Phagocytosis is a complex, evolutionarily conserved process that plays a central role in host defense against infection. We have identified a predicted transmembrane protein, Eater, which is involved in phagocytosis in Drosophila. Transcriptional silencing of the eater gene in a macrophage cell line led to a significant reduction in the binding and internalization of bacteria. Moreover, the N terminus of the Eater protein mediated direct microbial binding which could be inhibited with scavenger receptor ligands, acetylated, and oxidized low-density lipoprotein. In vivo, eater expression was restricted to blood cells. Flies lacking the eater gene displayed normal responses in NF-kappaB-like Toll and IMD signaling pathways but showed impaired phagocytosis and decreased survival after bacterial infection. Our results suggest that Eater is a major phagocytic receptor for a broad range of bacterial pathogens in Drosophila and provide a powerful model to address the role of phagocytosis in vivo.