English: In this research we applied ultrahigh-vacuum atomic force microscopy (UHV-AFM) for investigation of tobacco mosaic virus (TMV) and alfalfa mosaic virus (AMV) interaction with Si (1 1 1) surface. Changes of virion conformation and different degree of order on the investigated surface were established. It was demonstrated that adsorption of TMV virions is accompanied with formation of predominantly single-layered ordered films while AMV adsorption is accompanied with formation of unordered accumulations of the virions and more abrupt change of the height of viral particles. It was established that the change of virions’ height depended on the quantity of negatively-charged amino acid residues on the outer surface of capsid.