Seventeen parasite species (3 protozoans, 11 helminths, 2 arthropods, and 1 mollusc) were collected from 317 Atlantic salmon (Salmo salar), 207 brook trout (Salvelinus fontinalis), and 34 rainbow trout (Salmo gairdneri) in the 13 Canadian Maritime hatcheries during 1972. Four parasites, Camallanus oxycephalus, Pomphorhynchus bulbocolli, Hydrachna sp., and a glochidium, were recorded from Atlantic salmon for the first time. Incidence and intensity of infection were high for Trichophyra piscium, Diplostomulum spathaceum, and glochidia infecting salmon and for Acanthocephalus lateralis and Salmincola edwardsii infecting brook trout. Infection intensity of Apophallus imperator, D. spathaceum, S. edwardsii, and glochidia increased with host age. Apophallus imperator and S. edwardsii were host specific to brook trout and the glochidium was host specific to salmon. Sterliadochona tenuissima and A. lateralis were more abundant in brook trout than in salmon. Pathology was associated with infections of Hexamita salmonis, D. spathaceum, A. lateralis, and S. edwardsii.