We recently reported the photodynamic inactivation (PDI) of bacteriophage MS2 with a photosensitiser- 5， 10， 15， 20-tetrakis (1-methyl-4-pyridinio) porphyrin- tetra- p-toluene sulfonate (TMPyP) in solution and concluded that the A-protein of the virus is the main target of inactivation. Here， we have extended these studies and carried out PDI of bacteriophage Qβ， bovine enterovirus 2 (BEV-2) and type 1 murine norovirus (MNV-1). The rate of inactivation observed was in the order MS2 > Qβ > MNV-1 > BEV-2. Data suggested that TMPyP-treatment could also target the viral genome as well as result in disintegration/disassembly of viral particles. Although emergence of viral drug resistance is a well-documented phenomenon， it was not possible to generate PDI-resistant MS2. However， emergence of a mutation in the lysis protein was detected after serial exposure to PDI.