This case presentation will review tension pneumocephalus as a rare etiology of delayed posttraumatic headache (PTHA). It demonstrates that clinicians must be aware of even the uncommon causes of PTHA if appropriate diagnostic assessment and treatment are to be rendered. The case involves a 26-year-old right-handed white male who was 4 years post severe traumatic brain injury with facial fractures and an initial Glasgow Coma Scale score of 5. The patient's main postinjury functional impairments were cognitive–behavioral dysfunction, dysmetria, left hemiparesis, and posttraumatic epilepsy. Approximately 3 years post injury, the patient started to have complaints of right unilateral frontal headache. This complaint was addressed conservatively by several treating physicians. Due to the progressive nature of the patient's complaints, a second opinion was obtained with the author. On assessment, the patient complained of unilateral right headache and described the pain as making him feel as if his head was going to “bust open.” A computed tomography (CT) scan showed findings consistent with a tension pneumocephalus. The patient was referred to neurosurgery, at which time the tension pneumocephalus was evacuated and a dural leak, felt to be responsible for the condition, patched. The patient's headache complaints resolved postoperatively. Clinicians should be aware of uncommon conditions that may be present in patients presenting with late PTHA, particularly conditions such as tension pneumocephalus which may have a significant clinical morbidity.