In common white-toothed shrews, the vaginal smear was an inadequate indicator of receptivity. Nucleated epithelial cells usually predominated and most matings took place when the smear was of this type. Cornified cells in the smear in infrequent. Mating tests showed that virgin females 2 to 4 months old, were unreceptive for extended periods. Willingness to mate increased gradually with the age of the female. Females were receptive throughout pregnancy, suggesting a continuous secretion of oestrogen during gestation. There was a post-partum oestrus whether or not the young of the litter were being suckled, and an oestrus at the end of lactation. During mid-lactation, females were in a state of low receptivity, whether or not they were suckling.