Purpose: This protocol describes how to adsorb viruses onto TEM (transmission electron microscopy) grids. The sample is allowed to sit on a hydrophilic grid and viruses adsorb onto the surface of the grid. This technique is generally used for viral lysates with high concentrations of viruses. For natural samples, use the protocol “Quantitatively Depositing Viruses onto TEM Grids using an Airfuge”.Note: If purification of the viruses is necessary, refer to Ackermann and Heldal (2010) for various options.