Abstract and SummaryVaginal marking by female hamsters is more frequent in the presence of a male than when the female is alone; this is so on each of the three dioestrous days of the oestrous cycle. With a male present, marking frequency on Day 4 is about four times greater than on Day 2 or 3 of dioestrus. On Day 4, vaginal marking is correlated with male proximity and is greatest when the male is actively following the female. Vaginal marking is closely associated in time with the female moving away from the male, and particularly with rapid approach‐withdrawal by the female.Discussion centres on the function of vaginal marking. Vaginal secretion has at least two chemical fractions which have different effects on the male. It is likely that the context in which the male samples the vaginal secretion may modify the information that is transferred from the femal