Cross-sectional survey data were used to test whether personality traits were associated with a self-reported history of diagnosed sport-related concussions (SRC) and undiagnosed SRCs. A total of 1,398 of 2,055 (68%) collegiate student-athletes from four National Collegiate Athletic Association (NCAA) institutions voluntarily completed a one-time survey during their preparticipation physical examinations or a team meeting. Previously diagnosed SRCs and undiagnosed SRCs were measured with self-reports. The personality traits of neuroticism, extraversion, openness, agreeableness, and conscientiousness were captured via the 44-item Big Five Inventory. After exclusions, responses from 1,246 collegiate student-athletes (n = 702 males; n = 544 females; n = 727 SRC high-risk sport participants; and n = 518 SRC low-risk sport participants) were included for the final analyses. SRC history responses were grouped into 0, 1, and 2+ for diagnosed and undiagnosed. Nominal logistic regression models that included personality traits, demographics, and sport information were used for the primary analyses. No personality traits were found to be significantly related to 0, 1, or 2+ diagnosed SRCs. Agreeableness (p ≤ .01) was the only personality trait that was significantly associated with self-reporting 2+ undiagnosed SRCs compared with 0. One possible explanation is that broad personality traits may not be important risk factors for SRCs. Future studies should investigate specific individual differences that could be related to SRCs, such as risk-taking propensities and thrill-seeking tendencies. Likewise, future studies should use prospective designs to provide some constraints on inferences about the direction of the associations.