Preliminary studies conducted on rainbow trout (Salmo gairdneri) and white suckers (Castostomus commersoni) exposed to spruce budworm nuclear polyhedrosis virus revealed minor histopathologic changes in various organs of each fish which were interpreted as not being significant. However, an evaluation (mean values) of the total changes in groups of fish suggested that a relationship may exist in the suckers exposed to either purified polyhedra or virions. A more extensive and definitive study must be done before any conclusions are warranted.