Disclosed herein are methods of aiding in the diagnosis and evaluation of a subject that has sustained or may have sustained an injury to the head. For example, the present disclosure provides methods for aiding in the diagnosis and evaluation of a subject to determine whether the subject has sustained a traumatic brain injury (TBI) by detecting or measuring a combination of the levels of ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) and glial fibrillary acidic protein (GFAP) in samples taken at various time points within 48 hours after the subject has sustained or may have sustained an injury to the head.