Native brook trout were transplanted within the Ellerslie Brook System, Prince Edward Island, in summer, to determine how well they could compete with trout already resident in other habitats of the same stream. The resident trout in a habitat appeared to have a competitive advantage. This advantage was greater in habitats of low trout-carrying capacity. Transplanted trout fared better in partially depopulated habitats. Mortalities were higher among the transplanted trout during the ensuing 12-month period. Few transplanted trout homed to the area from which they had been displaced.