Sire breed has been shown to have a major effect on growth rate, carcass characteristics and meat quality of lambs from hill sheep systems (Carson et al 2001). A research programme has been initiated in Northern Ireland to improve the genetic potential of the hill flock through crossbreeding, with the crossbred females being retained on the hill and used as replacement breeding females. However, as information is also required on the performance of the crossbred male lambs, the first objective of the current study is to assess the effect of crossbred lamb genotype on carcass characteristics. Lamb meat is high in fat and low in polyunsaturated fatty acids. Vegetable oil-based diets have been shown to influence the fatty acid composition of meat (Solomon et al, 1991). Therefore the second objective of the current study is to evaluate the effect of offering diets containing oilseed rape on lamb meat quality.