Objective: To assess the specific effect of dizziness on psychosocial outcome after mild to moderate traumatic brain injury (TBI). Design: Six-month cross-sectional study. Setting: An outpatient TBI clinic in a tertiary care referral center. Participants: A consecutive sample of 207 adults with mild to moderate TBI, 138 (66.7%) of whom had subjective complaint of posttraumatic dizziness. Interventions: Not applicable. Main Outcome Measures: Psychosocial indices (Glasgow Outcome Scale [GOS], General Health Questionnaire [GHQ], Rivermead Head Injury Follow-Up Questionnaire [RHFUQ], return to work status) were collected from dizzy and nondizzy patients. Results: Despite similar demographic, TBI, and global disability (GOS) profiles of both groups, psychosocial functioning (GHQ, RHFUQ, return to work) was significantly worse in dizzy subjects (P<.01 for all indices). A logistic regression analysis identified dizziness (P=.006), total GHQ (P=.001) and psychotropic and analgesic use (P=.05) as significant independent predictors of reemployment. Conclusions: Although dizziness was closely linked to psychologic distress at 6 months after head injury, it also emerged as an independent predictor of failure to return to work, suggesting that not all its adverse effects on outcome are psychologically mediated. Clinicians need to be alert to the presence of dizziness as an adverse prognostic indicator after mild to moderate TBI. (C) 2004 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.