These internationally approved methods have provided accurate and timely information of animal and human rabies cases thereby supporting surveillance for rabies and providing a greater understanding of the epidemiology of this disease (Box 1). For numerous laboratories in rabies-endemic regions in the developing world, cost and simplicity are critical factors in the delivery of disease diagnosis and cannot be neglected, even when the principal consideration is for rapid diagnosis. Therefore, cost and simplicity need to be considered if new technologies are to be adopted in the regions of the world where they are most needed.