Headache attributed to head and/or neck trauma or injury, the so-called post-traumatic headache (PTH), is the most common secondary headache disorder and one of the most controversial clinical entities in the headache field, due to its unclear pathophysiological mechanisms and the unsolved role of associated psychological and medico-legal aspects. PTH, as a significant cause of morbidity after traumatic brain injury, may occur as an isolated symptom or as one of a constellation of symptoms known as post-concussive syndrome. However, in many cases, PTH might also represent an accentuation of non-disabling, remote or infrequent pre-existing primary headaches rather than a new onset headache strictly related to the trauma. Recently, the International Classification of Headache Disorders attempted to classify PTH; however, many unsolved issues are still to be clarified. In this brief review, we will focus on PTH clinical aspects and diagnostic criteria.