Fusarium wilt of Brassica crops is caused by the soil-borne pathogen Fusarium oxysporum f.sp. conglutinans (Wollenweb.). The symptoms are leaf yellowing, wilting, defoliation, stunted growth, and plant death. Previously, we observed the 3:1 segregation ratio of fusarium wilt resistance/susceptibility in the F2 progenies obtained from the cross between resistance double haploid (DH) line (Anju) and a susceptible DH line (GC), indicating that the resistance was controlled by a single dominant gene. This gene was named Foc-Bo1 and mapped to linkage group C7 by both the segregation test and quantitative trait locus (QTL) analysis. For fine mapping of Foc-Bo1, a number of EST markers were designed based on the high genome synteny with the Foc-Bo1 linkage markers and the corresponding regions of Arabidopsis thaliana and Brassica rapa genome. In addition, BSA8 and KBrS012D09 markers, located around the Foc-Bo1 locus, were used to select recombinant plants in a population of 1,012 F2 plants. The inoculation test using the progenies indicated that the Foc-Bo1 gene is located in a 0.7 cM segment between two markers.