Tall fescue (Festuca arundinacea Schreb.) is a cool season turfgrass widely used in home lawns, parks, and athletic fields. One of the most devastating diseases that can occur on tall fescue is brown patch, caused by the fungus Rhizoctonia solani Kuhn. Currently, chemical fungicides are the only effective control option to reduce disease severity. Genetic resistance utilized through the development of resistant cultivars would be a promising alternative to chemicals. Breeding cultivars for resistance to turfgrass pathogens has been successful for gray leaf spot (Pyricularia grisea (Cooke) Sacc.) in perennial ryegrass (Lolium perenne L.) and dollar spot (Sclerotinia homoeocarpa F.T. Bennett) in creeping bentgrass (Agrostis palustris L.). To determine the potential of breeding for resistance, the broad-sense heritability must first be calculated to determine if the trait is controlled by the environment or genotype. To calculate the broad-sense heritability of brown patch resistance in tall fescue, replicated field trials were planted in April of 2005 at two locations in central New Jersey. Each field trial consisted of 270 genotypes clonally replicated 6 times in a randomized complete block design and maintained as mowed spaced-plants at a height of 5.08cm. To ensure uniform disease pressure, each field trial was inoculated with two isolates of R. solani. Visual disease ratings were taken on a weekly basis when symptoms of the disease appeared using a scale of 1-9, with 9 representing the least amount of disease. The broad sense heritability calculated from the first year of data was H=0.76. This illustrates that resistance to brown patch is genetically controlled. Data from both years of the study will be presented.