Baboons face a serious threat of predation from leopards, Panthera pardus and lions, Panthera leo. Since trees and cliff faces provide safety from these predators, baboons might use such refuges in order to reduce predation risk. This hypothesis was explored in a study of four groups of chacma baboons, Papio cynocephalus ursinus in a desert population in Namibia (groups ranged between 22 and 55 individuals with one to six adult males). All baboons spent most of their time close by refuges and little time distant from them. This pattern was most accentuated among females in smaller groups. These females spent more time on refuges primarily as a result of greater refuge use during resting and grooming. This pattern was less clear during feeding and travelling, apparently owing to the constraints on refuge use imposed by the nature of these activities. A comparison of refuge use in high-risk and low-risk habitats (after the confounding effects of habitat-specific refuge availability had been removed) suggests that baboons might adopt one of two strategies in high-risk areas; if refuges are widespread they will use refuges more intensively, but if refuges are scarce they will adopt a time-minimizing strategy to leave the area as rapidly as possible. The baboons also increased their vigilance when refuges were distant. These results are consistent with the hypothesis that baboons use refuges to reduce predation risk.