Objectives Although mental health screenings are not routinely conducted in rugby, the Sport Concussion Assessment Tool - Fifth Edition (SCAT-5) is widely performed and measures affective, cognitive, sleep, and physical symptoms. This study investigated the psychometric properties of the SCAT-5 to explore its potential as a mental health screening tool. Methods During preseason for the 2021 Western Province Super League A in South Africa, clinicians conducted mental health assessments of 71 adult male rugby union players. The SCAT-5 Symptom Evaluation, Baron Depression Screener for Athletes (BDSA), Athlete Psychological Strain Questionnaire (APSQ), Center for Epidemiologic Studies-Depression (CES-D), and Generalized Anxiety Disorder-7 (GAD-7) were compared to each other and to fully structured diagnostic interviews by mental health professionals using the Mini International Neuropsychiatric Interview (MINI) 7.0.2. Results Lifetime MINI-defined mental disorders were common, being identified in 33.8% (95% CI 22.79-46.17%). Only 4.29% of participants had a previous diagnosis. Exploratory Factor Analysis indicated a mental health construct of depression/anxiety being measured by the SCAT-5. The SCAT-5 had strong internal consistency (alpha = 0.94) and showed moderate convergent validity with the CES-D (r = 0.34; p = 0.008) and GAD-7 (r = 0.49; p < 0.0001). The area under the curve for the ability of the SCAT-5 to identify current disorders was 0.87 (p = 0.003), on par with the CES-D and GAD-7. Conclusion Since the SCAT-5 has the potential to identify depression and anxiety, it may allow mental health screening without the need for additional measures. Follow-up studies should further explore its discriminative ability in larger samples.