Transmission Electron Microscopy (TEM) plays a major role in biological sciences and in the assessment of biological safety, particularly in virology. The technique allows visualization of virus particles, particle size, morphology, and intra- and extra-cellular location, both in biological fluids and in vitro. TEM methods are used extensively for the identification and enumeration of virus particles in both diagnostic virology and biological safety.1-11 TEM is recommended in several guidelines, specifying which materials require testing including: cell lines, culture supernatants and fermenter bulk harvests. Although relatively insensitive, TEM is a ‘catch-all’ test for viral detection which other techniques, such as in vitro and in vivo assays, or ‘specific’ molecular assays, such as qPCR, may miss.