Introduction: Abnormal electrocardiographic (ECG) findings can be seen in traumatic brain injury (TBI) patients. ECG may be an inexpensive tool to identify patients at high risk for developing cardiac dysfunction after TBI. The aim of this study was to examine abnormal ECG findings after isolated TBI and their association with true cardiac dysfunction, based on echocardiogram. Methods: Data from adult patients with isolated TBI between 2003 and 2010 was retrospectively examined. Inclusion criteria included the presence of a 12-lead ECG within 24 h of admission and a formal echocardiographic examination within 72 h of admission after TBI. Patients with preexisting cardiac disease were excluded. Baseline clinical characteristics, 12-lead ECG, and echocardiogram report were abstracted. Logistic regression was used to identify the relationship of specific ECG abnormalities with cardiac dysfunction. Results: We examined data from 59 patients with isolated TBI who underwent 12-lead ECG and echocardiographic evaluation. In this cohort, 13 (22%) patients had tachycardia (heart rate >100 bpm), 25 (42.4%) patients had a prolonged QTc, and 6 (10.2%) patients had morphologic end-repolarization abnormalities (MERA), with each having an association with abnormal echocardiographic findings: Odds ratios (and 95% confidence intervals) were 4.14 (1.02-17.05), 9.0 (1.74-46.65), and 5.63 (1.96-32.94), respectively. Ischemic-like ECG changes were not associated with echocardiographic abnormalities. Conclusions: Repolarization abnormalities (prolonged QTc and MERA), but not ischemic-like ECG changes, are associated with cardiac dysfunction after isolated TBI. 12-lead ECG may be an inexpensive screening tool to evaluate isolated TBI patients for cardiac dysfunction prior to more expensive or invasive studies.