We investigated the proportion of crab-eating macaques in the diet of Komodo dragons and quantified the spatial habitat use between the species as a proxy for predation threat and in relation to prey availability due to ecotourism. In 2013, in Loh Buaya valley of Rinca Island, Komodo National Park, we conducted macroscopic identification of hairs, claws, dentition and osteological remains of consumed prey. For habitat use, we quantified the use of vertical strata by macaques through focal animal sampling. For Komodo dragons in the valley, macaques were a significant component of their diet (20.7%), ranking second after rusa deer (58.6%); the proportion of macaques we observed in the diet is much higher than in previous studies. An increased use of the forest floor by macaques at this site may increase their vulnerability as a prey species, especially in the daytime when tourist presence impacts the availability of other favoured prey species.