The effect of three different viruses, i.e., alfalfa mosaic alfamovirus (AMV), broad bean mosaic bromovirus (BBMV) and bean yellow mosaic potyvirus (BYMV) on the cytopathic changes in cv. Giza Blanka ( Vicia faba L.) as well as their pathogenicity and effect on cells of affected host were studied. The viruses varied in their aggressiveness and effect on host cells, giving rise to various deformations and deterurations of host cell organelles and formed various types of cytoplasmic inclusions, in addition to vi rlons accumulations. ‘ The aggn‘siveness of virus isolates seemed to be corolated‘ to their cytopalhic effect on host cell organelles and was time dependant. AMV, with the greatest damaging effect on organelles, forming abundant virion accumilations but poor development oi inclusions {tubes and scrolls), was the most aggressive. BBMV, having less cytopathic effect, with abundant accumulation of virions but no formation of specific inclusions, was relatively, less aggrissive. BYMV showed a slight effect on host organelles with poor virions acoumilations but formed nomerous types of inclusions, was the lowest aggrissive. Viruses, with sphaerical virions tended to form no inclusions, with filamentous virions formed inclusions abundantly, of different types and that of multiple particles was intermediate in this respect.