Abstract Soft errors due to neutrons and alpha particles are among the main threats for the reliability of digital circuits operating at terrestrial level. These kinds of errors are typically associated with SRAMs and latches or DRAMs, and less frequently with non-volatile memories. In this paper we review the studies on the response of NAND and NOR Flash memories to ionizing particles, focusing on both single-level and multi-level cell architectures, manufactured in technologies down to a feature size of 25 nm. We discuss experimental error rates obtained with accelerated tests and identify the relative importance of neutron and alpha contributions. Technology scaling trends are finally discussed and modelled.