OBJECTIVE:To investigate the natural progression of olfactory impairment (OI) in individuals with traumatic brain injury (TBI) at 6 months postinjury. PARTICIPANTS:Forty-seven adults (mean age = 43.1 years, SD = 18.2), with predominantly severe TBI (mean posttraumatic amnesia [PTA] duration = 25.5 days, SD = 22.8). DESIGN:Consecutive admission longitudinal study. MAIN MEASURES:Participants were evaluated using the University of Pennsylvania Smell Identification Test (UPSIT) at resolution of PTA and at 6 months post-initial injury. Each participant was also interviewed to explore his or her experience of having an OI. Standard multiple regression was used to assess the ability of age, PTA duration, presence of facial fractures, and initial UPSIT score to predict olfactory performance at 6 months. RESULTS:Thirty-five participants (74%) continued to demonstrate OI at 6 months. Thirty-two participants (68%) showed some improvement, but only 12 of these individuals achieved scores within the normal range. The remaining 15 participants either produced a poorer performance (23%) or demonstrated no change (9%). Initial UPSIT score uniquely accounted for 73.5% of the variance in UPSIT performance at 6 months. CONCLUSIONS:Olfactory impairment persists in a substantial proportion of adults who experience it post-TBI and has the potential to impact a broad spectrum of everyday activities.