Objective: The Mild Brain Injury Atypical Symptoms (MBIAS) scale was developed as an embedded symptom validity test to be used in conjunction with postconcussion and PTSD symptom checklists. Ranging from 5 to 25, a score of >8 is considered invalid and indicative of symptom exaggeration. This study examined the MBIAS in a mixed clinical sample. Method: Participants were 306 US veterans (89.9% male; 38.6% African American, 59.5% Caucasian; Age: M = 53.0, SD = 16.8; Education: M = 13.1, SD = 3.6) who presented to an urban Department of Veterans Affairs Medical Center neuropsychology clinic with mixed etiologies. They completed the MBIAS as part of a larger test battery. Results: Average MBIAS total score was 7.2 (SD = 3.3) and Cronbach's α = .701. Individual items and total score were positively skewed and leptokurtic. The majority of the sample (50.7%) had the lowest possible total score, 69.0% generated a total score < 8, and 31.0% were deemed invalid. Item-total correlations ranged from r = .66 to r = .71. Item-item correlations ranged from r = .23 to r = .47. Multiple linear regression revealed that each item contributed significantly to the total score (all p < .001). Exploratory factor analysis demonstrated that all MBIAS items loaded onto a single factor. When each item was scored dichotomously, the mean total score was 0.7 (SD = 1.1). Most participants (60%) had a score of 0, 23% had a score of 1, 11% had a score of 2, and 7% had scores >2. Total scores of >2 comprised 18% of the sample. Conclusion: The MBIAS demonstrates good internal consistency in a mixed clinical sample, with each item contributing meaningfully to the total score.