Objectives: An ‘ultra-marathon’ is a footrace over a distance>42.2 km. There is considerable interest in thepsychological characteristics of ultra-marathon runners (‘ultra-runners’) and the psychological effects of runningan ultra-marathon. This review aimed to summarise the existing literature concerning the psychology of ultrarunners.Design: A systematic review was performed. Studies were included if they investigated ultra-runners’ personalitytraits, mood, cognitive processes, cognitive function, pain perception, motivations, phenomenology, psychopathologyor response to sports psychology interventions.Method: Four databases (PubMed, Scopus, Web of Science and PsycINFO) were searched electronically up untilDecember 2017.Results: Fifty-one studies met the inclusion criteria. A few conclusions regarding the psychology of ultra-runnersmay be drawn from these studies. First, the acute mood effects of ultra-running appear to include an increase infatigue and a decrease in vigour and tension. Secondly, the most important factor motivating ultra-runners toengage in their sport appears to be the opportunity to achieve personal goals. Finally, ultra-running seems to beassociated with a psychological drive to explore physical and mental limits.Conclusions: Although the existing literature sheds some light on ultra-runners’ mood states, motivations andphenomenology, further high-quality studies investigating the psychology of these remarkable athletes areneeded.