Reverse mounting (RM), i.e. where the female mounts the male, has been recorded in some bird species, yet the potential function of this behaviour is not clear. Here, we describe the frequency of RM in the brown booby Sula leucogaster and the behavioural context in which it occurs. We found that 12% (4 out of 33) of focal pairs performed RM. Time spent at the territory and intra-pair courtship and copulations did not differ between RM and non-RM pairs. Females that performed RM were more prone to engage in extra-pair courtship than females that did not perform RM, and male partners of females that performed RM were more likely to engage in extra-pair copulations; however, the probability of laying a clutch did not differ between RM and non-RM pairs. Hence, in the brown booby our data suggest that it is unlikely that RM plays a role during courtship by strengthening pair formation or pair bonds. The potential functional role and the mechanisms modulating RM in promiscuous females need to be further investigated.