Previous reports have suggested that both repetitive head trauma and a single injury can be associated with the presence of diffuse beta A4 amyloid protein plaques in long-term survivors. We have studied sixteen patients (aged 10-63 years) who sustained head injury and survived for only 6-18 days. Immunostaining with an antibody to beta A4 amyloid showed extensive deposits of the protein in the cortex in six of the sixteen patients (38%). Thus, severe head injury can trigger beta A4 deposition in the brain within days.