TBI may refer to:
- TBI plc, an airport owner and operator
- Tennessee Bureau of Investigation, the criminal investigative arm of the state government of Tennessee
- The Bourne Identity
- Total body irradiation, a form of radiation therapy used most commonly in bone marrow transplantation
- Tracheobronchial injury, an injury to the trachea or main bronchi
- Trade Bank of Iraq, a publicly owned bank headquartered in Baghdad, Iraq
- Traumatic brain injury, a physical trauma to the brain
- Throttle Body Injection, a type of fuel injection system used on internal combustion engines
- TBI Solicitors, a UK-based law firm
- Task-based instruction, an alternative name for task-based language learning, an approach to language learning and language teaching