A survey of the woody plants was conducted during a ten year period (1985-95) at the Rock Creek Research Natural Area (RCRNA) gorge, a 77 ha old-growth stand of Hemlock-Mixed Mesophytic Forest, and its 353 ha upland watershed. The study site is located in the London Ranger District of the Daniel Boone National Forest in Laurel County, Kentucky, at the extreme western edge of the Northern Cum berland Plateau. The annotated catalogue consists of 117 (112 native, 5 exotic) woody species in 77 genera from 43 families. Five plant community types described are the old-growth Hemlock-Mixed Mesophytic Forest and Riverine Floodplain Forest of RCRNA, and the Pine-Oak Forest, Oak-Hickory-Pine Forest, and clear-cuts (7-year old and 35-year old) of the watershed uplands. Geographical floristic affinities of the woody plants reveal that 87 are intraneous, 25 are extraneous, and five are naturalized. The S0rensons Index of Similarity is 78.8% between RCRNA and its uplands and Robinson Forest, and 84.7% between RCRNA and its uplands and Lilley Cornett Woods, two other mixed mesophytic forest stands with old growth remnants in the Northern Cumberland Plateau.