Olfactory impairment (OI) can present in up to 66% of all individuals following traumatic brain injury (TBI) and can have significant implications for everyday life.To investigate the predictive factors, natural progression and consequences of OI following TBI in individuals 12 months post injury.In this prospective longitudinal study, 37 adults (28 males, 9 females), mean age 42.3 years (SD 19.4), with predominately severe TBI (mean length of posttraumatic amnesia (PTA) 28.6 days, SD 22.6) were assessed using the University of Pennsylvania Smell Identification Test (UPSIT). Each participant also participated in an open ended interview to allow exploration of their experience of having OI.Thirty (83.33%) of the participants demonstrated persisting OI at 12 months. Nineteen of these participants demonstrated no change in their OI severity category and 4 produced a poorer performance. Thirteen participants (36.11%) demonstrated some recovery with 6 of these performing within the 'normal' range for age andgender.OI is an enduring impairment for a substantial proportion of individuals who experience it following severe TBI. It impacts a range of everyday activities, regardless of its severity, and requires comprehensive management during rehabilitation.