We reviewed pre-admission diagnosis in all patients referred for inpatient brain injury neurorehabilitation over a 5-year period (n = 193). All patients more than 1 month postinjury with diagnosis of coma or persistent vegetative state were selected for review (n = 49). We found that 18 (37%) of these patients were diagnosed inaccurately. Inaccurate diagnosis was more likely if the injury was more than 3 months before admission and the etiology of injury was trauma (48%). Results were statistically significant when traumatic injuries were compared with anoxic injuries (p < 0.10). Errors in diagnosis may result from confusion in terminology, lack of extended observation of patients, and lack of skill or training in the assessment of neurologically devastated patients.