The upper 46 miles of the North Fork of Licking River in Mason County, Kentucky, were treated in July, 1952, with 5-percent powdered rotenone to eradicate the entire fish population. This experimental section was then left open at all times to rough fish movement and recruitment. North Fork was selected as being typical of the many warm-water streams in the state having a high rough fish population which once offered better than average game fish angling. Five random population samples totaling 2.88 acres in area were taken prior to the eradication operation. They yielded 2,662 fish weighing 466.49 pounds. Game fish species occupied only 4.51 percent by number and 6.54 percent by weight of the total population. These samples revealed the stream was supporting an average of 161.98 pounds of fish per acre. Restocking of game and pan fishes was begun one week after eradication. A total of 18,717 game fish (largemouth bass, black crappie, and white crappie) were released at 14 different locations. At these same locations 12,540 bluegill and longear sunfish were restocked. Population studies conducted in the original five areas one year after eradication showed that game fish species occupied 5.81 percent by number and 6.90 by weight of the total population. The standing crop of all species of fish combined was only 81.52 pounds per acre. This figure is approximately one-half of the previously determined carrying capacity. This investigation is being continued and the changes in species composition and stream production will be closely followed.