Engineered nanomaterials, defined as having at least one dimension smaller than 100 nm, have revolutionized many technology sectors ranging from therapeutics and diagnostics to environmental monitoring and remediation. This has resulted in a rapid increase in their manufacture over the past few years, accompanied by an increased human exposure potential. However, understanding of the interactions of nanomaterials with biological systems is still rudimentary. We have described that an environmentally and medically relevant nano metal (cerium dioxide) can affect primary human monocyte viability and interact with programmed cell death pathways leading to apoptosis and autophagic cell death. Cerium dioxide nanoparticles (CeO 2 NPs)-induced autophagy acts as a prodeath mechanism and leads to increased cytotoxicity of human monocytes. A better understanding of the implication and biological significance of CeO 2 NPs-induced autophagy and apoptosis will help us understand the risks associated with its uses and develop safer nanomedicine.