This study aimed to describe the recovery of impairments after severe traumatic brain injury (TBI) over a 3-year period. An inception cohort over 2 years was recruited from 11 brain injury rehabilitation units participating in a state-wide program. The 131 individuals with TBI were assessed at admission to the rehabilitation program, 18 months and 3 years post-trauma. This report described results from the Disability Rating Scale (DRS) and Mayo-Portland Adaptability Index (MPAI). Regression analyses, examining the influence of five acute injury variables on DRS and MPAI, revealed that posttraumatic amnesia (PTA) was a significant individual predictor. Data were thus analysed according to duration of PTA: 1 to 2 weeks (n = 19), 2 to 4 weeks (n = 44) and more than 4 weeks (n = 68). At program admission there was poorer overall level of functioning on the DRS in the longest PTA group, but no difference between the shorter PTA groups. Significant improvements occurred on the DRS for all PTA groups over the first 18 months posttrauma, with improvements continuing between 18 months and 3 years. At the 3-year follow-up, frequency data from the MPAI indicated that clinically significant impairments in mobility, hand function, communication and behaviour were uncommon in the shorter PTA groups, although 36% to 47% continued to experience cognitive impairments. Impairments were common in the longest PTA group in some areas, particularly cognition where two thirds or more continued to experience clinically significant impairments in attention, memory and novel problem-solving. These results confirm the predictive significance of PTA duration regarding longer-term level of recovery. They also highlight the limitation in classifying the ‘severe’ TBI category as an homogenous group: significant subgroup differences occurred on medical and functional variables at program admission, 18 months and 3 years posttrauma. These data further substantiate the persistence of neuropsychological impairments in the face of good physical recovery at all levels of severity within the severe TBI group.