OBJECTIVES: Considering the increasing applications of silver nanoparticles (AgNPs) in food- and cosmetic-related products worldwide, the aim of this study was to investigate the potential adverse health effects induced by AgNPs exposure in terms of cytotoxicity, oxidative stress, and mitochondrial injury in human A549 and HepG2 cells. METHODS: After a 48 h AgNPs treatment, the cell viability was measured by MTT assay. Oxidative damage was determined by assays of malondialdehyde (MDA), 8-epi-PGF2α and 8-hydroxy-2'-deoxyguanosine (8-oxo-dG). The protein expression of HSPA1A and HO-1 was analyzed by western blot analysis. Mitochondrial membrane potential (MMP) was detected by using JC-1 as fluorescent probes. The uptake and intracellular localization of AgNPs was measured by transmission electron microscopy (TEM), and cellular AgNPs was determined by inductively coupled plasma mass spectrometry (ICP-MS). RESULTS: A dose-dependent decrease in cell viability after AgNPs treatment was observed, which was associated correspondingly with oxidative damage as indicated by increases in MDA amount, 8-epi-PGF2α and 8-oxo-dG levels, HSPA1A and HO-1 expression, as well as mitochondrial injury as indicated by decreased MMP. The cellular uptake of AgNPs measured by ICP-MS analysis was correlated correspondingly with the oxidative damage and mitochondrial injury. CONCLUSIONS: The dose-dependent cytotoxicity induced by AgNPs may result from an interaction of oxidative stress, DNA damage and mitochondrial injury in A549 and HepG2 cells. ? 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1691-1699, 2016.