It is a general strategy for mammalian females to emit odour signals to direct their offspring to the mammae and to motivate their suckling. The survival of newborns depends on their own capacities to exploit the cues emitted by their mother, or by conspecific lactating females, and to direct their behaviour to the vital targets on the mother's body-the nipples. This chapter synthesises data on some natural substrates that contribute to nipple searching and grasping in the newborns of (laboratory strains of) two phylogenetically close species, Rattus norvegicus and Mus musculus