The high elevation beech gaps of the Great Smoky Mountains have become the killing front of beech bark disease. This insect/fungal pathogen was introduced into Nova Scotia in the late 1800's, and has since spread southward to the Southern Appalachians. In affected stands, mortality of beech stems frequently approaches 90 to 100 percent. We used inter-simple sequence repeats (ISSR) markers to assess the relationship between host genotype and degree of pathogen infection in beech trees in Great Smoky Mountains National Park. We used statistical analyses to test the relationship between stem diameter and degree of pathogen infection. We found no correlation between host genotype and degree of infection. We did find a significant positive relationship between stem size and degree of infection. Among three stem size classes, smallest stems (<1.5 cm) were least likely to be infected, while largest stems (>3.0 cm) were most likely to be infected. Implications for future studies are discussed.