Associations between animals of different species have been observed for a large variety of taxa. These polyspecific groups are thought to provide advantages to at least one of the species involved, especially foraging benefits or reduced predation risk. In the case of primate-bird associations, both foraging benefits and reduced predation risk have been suggested. We investigated whether flocks of Crested Guineafowl (Guttera edouardi) join groups of samango monkeys (Cercopithecus albogularis schwarzi) and examined benefits to the birds. Using behavioural data, we tested (1) whether Crested Guineafowl associate with samango monkeys for a longer period of time than can be expected by chance, using a movement simulation model, and (2) whether Crested Guineafowl show differences in foraging and predation risk behaviour and habitat selection in relation to vegetation cover in the presence of samango monkeys. Observations were done in the Soutpansberg Mountain Range, South Africa. We found that (1) Crested Guineafowl join samango monkeys for a longer period of time than expected by chance, and (2) Crested Guineafowl show significantly less sentinel behaviour with samango monkeys present. These findings suggest that the birds experience reduced predation risk in the presence of the monkeys. Our study is the first to report association between Crested Guineafowl and samango monkeys and contributes to understanding why birds and primates associate.