In Kenya knowledge of the relative severity of threats to protectedareas and the vulnerability of these areas to any threats islacking. Such information is required, however, for assessment ofthe effectiveness of management of the country’s protected areas,and to help identify critical management and policy weaknesses andpriorities for improving management and allocating resources. Wetherefore studied the relative severity of threats to Kenya’s 50protected areas and their relative vulnerability to such threatsbased on the perceptions of protected area managers. Ten threatswere identified by these managers, of which the most severe wereillegal bushmeat hunting, poaching of large mammals, human–wildlifeconflicts, human encroachment, and loss of migration corridors anddispersal areas. Thirty-two (64%) protected areas were vulnerable toover half of the threats, 54% vulnerable to over six of the threatsand 32% vulnerable to over seven of the threats. Protected areas inmarine, forested/montane and inland wetland ecosystems were regardedas highly vulnerable to the perceived threats. Protected areasadjacent to urban/industrial and agricultural areas were vulnerableto most of the threats. Our findings demonstrate that protectedareas in Kenya are increasingly threatened, that major threats needsto be mitigated, and that prioritization of protected areas forstrategic actions is required for effective management.