OBJECTIVE:To identify, for patients in states of seriously impaired consciousness, comorbid conditions present during inpatient rehabilitation and their association with function at 1 year. DESIGN:Abstracted data from a prospective cross-sectional observational study with data collection occurring January 1996 through December 2007. SETTING:Four inpatient rehabilitation facilities in metropolitan areas. PARTICIPANTS:The study sample of 68 participants is abstracted from a database of 157 patients remaining in states of seriously impaired consciousness for at least 28 days. INTERVENTIONS:Not applicable. MAIN OUTCOME MEASURE:One-year cognitive, motor, and total FIM score. RESULTS:The most common medical complications during inpatient rehabilitation for the study sample are active seizures (46%), spasticity (57%), urinary tract infections (47%), and hydrocephalus with and without shunt (38%). Presence of ≥3 medical complications during inpatient rehabilitation, controlling for injury severity, is significantly (P<.05) associated with poorer total FIM and FIM motor scores 1 year after injury. The presence of hydrocephalus with and without shunt (r=-.20, -.21, -.18; P ≤.15), active seizures (r=-.31, -.22, -.42), spasticity (r=-.38, -.28, -.40), and urinary tract infections (r=-.25, -.24, -.26) were significantly (P<.10) associated with total FIM, FIM cognitive, and FIM motor scores, respectively. CONCLUSIONS:Reported findings indicate that persons in states of seriously impaired consciousness with higher numbers of medical complications during inpatient rehabilitation are more likely to have lower functional levels 1-year postinjury. The findings indicate that persons with ≥3 medical complications during inpatient rehabilitation are at a higher risk for poorer functional outcomes at 1 year. It is, therefore, prudent to evaluate these patients for indications of these complications during inpatient rehabilitation.