OBJECTIVE: The purposes of this study were to estimate the incidence and complications of the tracheostomy and after decannulation, and to compare the functional outcomes between tracheostomy and non-tracheostomy groups in the severe traumatic brain injury (TBI) patients. METHOD: One hundred and fifteen severe TBI patients were included in this study and the functional outcomes were measured by the Functional Independence Measure (FIM) scores retrospectively. RESULTS: The incidence of tracheostomy was 45.2% and the average duration of tracheostmy was 69.7 days. Twenty seven complications associated with the tracheostomy (51.9%) were reported and a pneumonia was the most common complication. Fourteen complications (26.9%) were reported after the decannulation and a tracheal granuloma was the most common complication. Complications mostly occurred during the first two weeks of tracheostomy. The duration of rehabilitation treatment for the patients with tracheostomy was longer than the patients without tracheostomy. TBI patients with tracheostomy had significantly lower initial and discharge FIM scores, FIM gain, and FIM efficiency than the patients without tracheostomy. CONCLUSION: The complications of tracheostomy were mostly occurred early in the acute stage. Functional outcomes were lower in severe TBI patients with tracheostomy, thus early comprehensive and aggressive rehabilitation treatments would be necessary.