Fluids and Barriers of the CNS is an open access, peer-reviewed journal that considers manuscripts on all CNS fluids and barrier systems in health and disease.Homeostatic maintenance of the internal environment of the nervous system through normal functioning of brain fluids and barriers is vital for health of the organism. The cerebrospinal fluid (CSF), its composition, circulation and absorption, has multiple roles in both normal and abnormal brain function and is closely associated with the parenchymal interstitial fluid and the neurovascular unit at the blood-brain barrier. The CNS fluids and barrier systems including the blood-CSF barrier, the blood-brain barrier, the blood-retinal barrier and the blood-nerve barriers, perform functions such as fluid secretion, chemical signalling, physical and chemical buffering, specialised directional transport and facilitation of immune surveillance.