In the early 1970's, Cutler, Lorenzo, Barlow and their colleagues (Brain, 1968; Brain, 1970; Arch. Neurol., 1974) carried out fundamental studies of infants with hydrocephalus which provided much of the current knowledge of cerebrospinal fluid (CSF) production and absorption. By adapting the ventricular-lumbar perfusion technique to study of humans these investigators made a series of quantitative studies of CSF formation and absorption. The normal rate of CSF formation was measured and was found to be essentially unchanged in human hydrocephalus, except in choroid plexus papilloma where CSF formation was greatly increased. The absorption of CSF was shown to begin at a critical pressure. In normal individuals, a linear relationship between the rate of CSF absorption and increase in intracranial pressure was shown, and several patterns of deficient absorption were identified with hydrocephalus. This work serves in part as the foundation for current Children's Hospital IDDRC studies of infantile hydrocephalus using exciting new techniques of near-infrared spectroscopy and diffusion-based magnetic resonance techniques.