Background: Although head injury (HI) is a major public health problem in Nigeria and other low and middle income countries of the world, there is a paucity of data from these societies. This is largely due to under-reporting. We carried out a prospective study of the clinicoepidemiological profiles and outcomes following the first hospitalization of a cohort of head-injured patients in Ikeja, Nigeria, a metropolitan African city. Methods: In an 8-month period from May until December 2005, data from all HI cases seen in our neurosurgical unit were prospectively recorded for subsequent analysis. These include demographics, mechanism of injury, pre-neurosurgical care received, severity of injury using the Glasgow Coma Scale, presence of hemodynamic instability, pupillary anomalies and associated systemic injuries, cranial computed tomography (CT) findings and the number of surgical interventions, as well as outcomes after the first hospital admission using the Glasgow Outcome Scale. Determinants of outcome were explored using the χ2 test and the level of significance was put at p = 0.05. Results: There were 143 cases of HI, which is about one fifth of our total workload, including 122 males and 21 females aged 0.5–85 years (mean age 29.15). The majority (88%) were either school children or low income earners. Road accidents accounted for 75% of the cases; three quarter of the cases had some initial care in other health facilities before the arrival in our unit, at an average of 33 h. Mild, moderate and severe HI accounted for 60, 18 and 22%, respectively. About a quarter of the patients sustained other systemic injuries. Cranial CT scanning was obtainable in 40 patients (28%); 9 of these revealed surgical mass lesions, of whom 5 had life-saving operations. Many well-known determinants of a poor outcome of HI were prevalent in this study group and found to have a significantly adverse effect on patient outcome. Conclusions: HI is a major public health problem in Nigeria, taking up at least one fifth of the neurosurgical workload. The prehospital emergency medical service is poorly organized. Determinants of a poor outcome of HI are highly prevalent, including poor accessibility to cranial CT scanning, absence or inadequacy of logistics for neurocritical care and an inadequate number of neurosurgeons.