Adult fall-run chinook salmon (Oncorhynchus tshawytscha) were studied during plunging and streaming conditions of flow in a pool-and-overfall fishway that permitted recycling of fish after each completed circuit. Flows were controlled by adjustment of valves in a lock at the head of the fishway. Individual fish were timed as they ascended a specified number of pools under each condition. Combined data on the performance of individual fish and comparisons of combined data from all fish tested suggest that plunging and streaming flows may be equally suitable for the passage of chinook salmon in a pool-and -overfall fishway. About 60 percent of the fish ascended slightly faster in the streaming flow, but the average rate of ascent for all fish was slightly higher in a plunging flow. Orientation of the fish is described in relation to type and velocity of flow. Most fish preferred to rest in the lower downstream quadrant of the pool in a plunging flow; conversely, the lower upstream quadrant was preferred in a streaming flow. Resting fish always faced the current.