This chapter focuses on forensic aspects of traumatic and natural subarachnoid haemorrhage. Subarachnoid haemorrhage is a common finding in association with primary traumatic intracranial injuries such as extra-axial bleeds and brain contusions. Subarachnoid haemorrhage may stimulate a very rapid neutrophilic inflammatory response. True traumatic basal subarachnoid haemorrhage is a well-validated forensic entity, although not infrequently underrecognised leading to suboptimal investigation. The term should be reserved for the specific entity of damage to the vertebrobasilar vasculature in association with trauma, most commonly a blow, to the head and neck, resulting in neck hyperextension and rotation, effectively twisting and tilting the head on the neck. The removal of the extracranial vertebral arteries for histological assessment can be achieved by en bloc excision of the cervical spine with the base of skull, with subsequent decalcification and dissection or serial ‘bread’ slicing.