The purpose of this study was to determine if juvenile Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) can discriminate kin from non-kin, since other salmonid species (coho salmon (Oncorhynchus kisutch) and Arctic charr (Salvelinus alpinus)) have been shown to possess this ability. When tested in water conditioned by conspecifics (kin and non-kin) and heterospecifics in a two-choice tank, both rainbow trout and Atlantic salmon demonstrated a significant preference for kin over non-kin and heterospecifics, indicating that these species possess kin-discrimination abilities. This ability appears to be widespread among salmonid fishes.