Six Rubus idaeus cultivars (Malling Admiral, Malling Orion, Glen Clara, Malling Promise, Malling Landmark and Malling Jewel) of differing growth habits and yield potentials were grown under annual and biennial cropping systems. The directions of changes in yield components in response to biennial cropping were the same in all cultivars, but the degree of change differed between cultivars. Berry size was little affected. Yield per cane and per cropping node were lower than with annual cropping but the reduction was small compared with the increase in numbers of cropping nodes and cane numbers, which resulted in heavier yields/ha in the fruiting years. The cultivars Malling Admiral and Malling Orion produced higher mean annual yields from biennial than from annual cropping systems, but the other 4 cultivars showed yield decreases. There was no relation between yield of a cultivar on the annual system and its degree of response to biennial cropping. The 2 cultivars which responded best to biennial cropping did so because of marked increases in cane number and in the number of cropping nodes/cane, compared with annual cropping. On the annual system these 2 cultivars had fewer and taller canes than the other 4 cultivars.