The objective of this study was to test the hypothesis that sleep quality mediates the association between traumatic brain injury (TBI) history and current suicidal ideation. Measures of TBI history, sleep quality, and suicidal ideation were administered to 130 Iraq/Afghanistan veterans. As expected, sleep quality mediated the effect of TBI history on current suicidal ideation (indirect effect, 0.0082; 95% confidence interval, 0.0019-0.0196), such that history of TBI was associated with worse sleep quality, which was, in turn, associated with increased suicidal ideation. These findings highlight the importance of assessing TBI history and sleep quality during suicide risk assessments for veterans.