Technical Abstract: Thirty Plant Introductions (PI) from the USDA-ARS National Plant Germplasm System were evaluated for resistance to Rhizoctonia root rot. Materials were planted at the Crops Research Lab-Fort Collins Research Farm in CO and inoculated with dry, ground, barley-grain inoculum of Rhizoctonia solani isolate R-9. Immediately after inoculation, a cultivation was performed to throw soil into the beet crowns. At harvest, each root was rated for rot on a scale of 0 (no damage) to 7 (completely rotted). Analyses of variance were performed on disease indices (DI), percent healthy roots (undamaged classes 0 and 1 combined), and percentage of roots in classes 0 thru 3 (those most likely to be harvested and taken to the factory). Percentages were transformed using arcsine-square root to normalize the data for analyses. Good disease developed by mid-September. Differences in DI among entries were highly significant (P < 0.001). Mean DI across all tests in the 2004 nursery for highly resistant FC705-1, resistant FC703, and highly susceptible FC901/C817 controls were 2.7, 3.1, and 4.9 respectively. Percentages of healthy roots were 27.6, 25.4, and 6.4%