The fossa (Cryptoprocta ferox) is the top terrestrial predator in Madagascar and a known threat to lemurs. To reduce the risk of predation, lemurs may rely on chemical cues (scents) left by fossa in the environment in order to accurately evaluate their immediate endangerment. We used camera traps to study predator-prey interactions, focusing on the scent-marking behavior of the fossa and subsequent responses of lemurs to those scent-mark sites in Maromizaha, an eastern rainforest in Madagascar. Our data showed that the fossa is active day and night. Lemurs, of diurnal or nocturnal habit, also visited the scent-mark sites during both day and night. Several species of lemur, such as indri (Indri indri), diademed sifaka (Propithecus diadema), brown lemur (Eulemur fulvus), eastern lesser bamboo lemur (Hapalemur griseus), eastern woolly lemur (Avahi laniger), and small-toothed sportive lemur (Lepilemur microdon), did not avoid the scent-mark sites. Quite to the contrary, individual lemurs were observed to feed, rest, play and even sniff and scent-mark over the mark of the fossa. Because the home range of the fossa is large relative to that of sympatric lemur species, it is likely that only one fossa overlaps the range of a group or an individual of a particular lemur species. Because the volatiles of fossa scent may communicate an individual’s identity, our results suggest that, although risky, assessing these scent marks may provide resident lemurs with information essential for the spatial/temporal use of their home range.