BackgroundTrauma is highly prevalent in bipolar disorder, and while considerable research has been undertaken in relation to childhood trauma, little is known about the experience and the impact of exposure to multiple trauma types across the lifespan, otherwise known as cumulative trauma. This study aimed to examine the prevalence of cumulative trauma in bipolar disorder and explore its association with illness and other outcomes. MethodsParticipants were recruited online globally and comprised 114 adults aged 23 to 73 years with BD-I (41.2 %) or BD-II (58.8 %). Participants completed an online questionnaire containing items regarding symptoms and trauma history followed by a diagnostic interview to confirm their BD diagnosis and assess BD symptoms. ResultsCumulative trauma accounted for most of the trauma exposure across both childhood (n = 89; 78.1 %) and adulthood (n = 72; 63.2 %). Those with lifetime cumulative trauma (n = 64; 56 %) were more likely to experience at least one other co-morbid mental health condition in addition to their BD diagnosis (88 %) and report significantly lower ratings of perceived social support compared to those who did not experience any cumulative trauma (N = 15; 13 %). LimitationsThis study has been limited by the cross-sectional retrospective design as well as the use of self-selection to participate. ConclusionsCumulative trauma is highly prevalent in bipolar disorder and is associated with greater likelihood of experiencing a psychiatric comorbidity and decreased levels of social support. More research is needed to explore the nature of this relationship and determine whether increasing social support may be of benefit.