This work has characterised cultivar resistance to Fusarium head blight (FHB) and brown foot rot (BFR) in wheat caused by Fusarium culmorum. In vitro assays were used to investigate the relationship between phenotypic FHB resistance and possible mechanisms involving tolerance to deoxynivalenol (DON) and antifungal activity of protein extracts from grain. Quantitative trait loci (QTL) for individual components of FHB resistance were mapped in winter wheat using doubled haploid progeny lines (DHL) from a cross between Hobbit 'sib' and the FHB resistant cultivar WEK0609. In addition, the genetic relationship between QTL for FHB resistance and certain aspects of plant morphology, habit and yield was also assessed. Resistance to FHB and BFR was not correlated in the germplasm studied indicating that resistance to the two phases of the disease was independent . In general, AUDPC was a good indicator of relative yield and fungal biomass (F. culmorum-specific quantitative peR) at the ear, however, levels of fungal biomass at the stem base were frequently underestimated. Low correlation between FHB resistance, antifungal activity and in vitro DON tolerance, indicated that the mechanisms underlying such assays may be a relatively unimportant component of resistance in WEK0609. Significant correlation between visual and underlying measures of disease spread (relative yield and fungal biomass) suggests that resistance to colonisation dominates WEK0609 resistance. Classical genetics indicated that heritability for symptom development in WEK0609 was high (0.7 to 0.8) and based on two or three genes of additive effect. Major QTL for components of WEK0609 FHB resistance that reduced DON content and increased yield tolerance were detected on the long anns of chromosomes 2D and SA respectively. The QTL on SAL was associated with QTL for increased in vitro DON tolerance, awning, spikelet weight and plot yield, and reduced spike density. This is the first study to identify the genomic location of FHB resistance in winter wheat.