The interaction between vegetative and fruiting canes of red raspberry was examined at sites in Scotland and N. America, using a range of cvs. In the absence of vegetative canes, yields from fruiting canes were increased and in the absence of fruiting canes greater numbers of vegetative canes were produced. Separating the 2 phases in this way produced a biennial cropping system, in which the yield in the cropping year was considerably higher than in the conventional annual system. Cvs varied both in the magnitude of their responses and in the nature of the changes in yield components influencing productivity. Among the cvs tested the greatest response was obtained from Norfolk Giant, where cane numbers and yield/cane both contributed significantly to enhanced yield. The implications of these results for cultural methods and cv. testing are discussed.