Despite the increased evidence and acceptance of exercise being classed as a behavioral addiction, there is limited research examining personality characteristics within exercise addicts. The purpose of this study was to examine three personality traits (narcissism, extraversion, and agreeableness) and to examine their role in exercise addiction. The sample comprised 114 voluntary participants (74 females and 40 males) who completed the (i) Exercise Addiction Inventory, (ii) Narcissistic Personality Inventory, and (iii) Ten-Item Personality Inventory, as well as demographic questions and questions concerning their engagement and intensity levels of exercise. Results indicated a low incidence of individuals who were classed as at risk of exercise addiction (7%), but a high incidence of symptomatic individuals (75%). Results suggested that extraversion and narcissism may be underlying factors in exercise addiction with no effect for agreeableness. Exercise engagement and intensity were also related to exercise addiction. Further research examining the relationship between personality types and exercise addiction may be useful in identifying individuals at risk for developing exercise addiction.Keywords Exercise addiction . Personality factors . Narcissism . Extraversion . Agreeableness Exercise participation is typically seen as a healthy behavior that enhances both physical and psychological wellbeing (Fox 1999). However, excessive physical activity can have detrimental effects where it may manifest into a potential addiction if it starts to become a compulsive activity in an individual's day-to-day life (Hausenblas and Downs 2002). The shift in how addiction has changed has been significant in the last few decades with the DSM-5 (American Psychiatric Association 2013) altering the previous category of Bsubstance-related disorders^to one that also considers behavioral addictions. At present, the only behavior that is officially Int J Ment Health Addiction