Book excerpt: Brain edema is a simple phenomenon – an abnormal increase of brain tissue volume by the increase of brain tissue water content. However the etiology is not simple and relating to a wide variety of neurological disorders including ischemia, trauma, tumor, hemorrhage and hydrocephalus. It is still a major cause of death in the neurological/neurosurgical ward. This volume is an up-to-date report on progress in brain edema research, diagnosis and treatment, including papers presented at the 12th International Symposium on Brain Edema and Brain Tissue Injury in 2002. Major topics include molecular biology and blood-brain barrier disorders, ischemic and traumatic brain edema, imaging and diagnosis of brain edema, treatment and radiation effect. Various papers in the rapidly growing fields of neuroimaging and molecular medicine are also included.