The responses of 56 cotton-top tamarin monkeys (Saguinus oedipus) to the faecal scent of predators and non-predators were recorded to determine if there was a differential response. Methylene chloride extracts were prepared from the faeces of suspected predators (margay and tayra) and non-predators (capybara and paca) known to co-exist with the tamarins in the wild The faecal extracts were presented to the tamarins on wooden dowels in their enclosures. Untreated dowel and dowel treated with methylene chloride served as controls. The tamarins exhibited high anxiety responses to predator scent compared to non-predator scent which produced low anxiety responses. No sex differences were found but an age difference was apparent: younger individuals were more curious than their elders. The response pattern was observed in captive-born individuals and was not affected by whether or not their parents were wild-caught or captive-born. This indicates that the discrimination of predator and non-predator scents is innate. However, this should not be taken to mean that captive cotton-top tamarins should be re-introduced to the wild without prior predator avoidance training. The implication of this study for animal welfare is that in captive environments where both predator and prey species are kept, it is important that predators, and their faeces, are not situated where prey species can detect their presence through olfaction, because prey species may suffer continual levels of heightened anxiety with possible detrimental effects.