Abstract: Apparatus and method are disclosed for indicating and regulating the pressure of a selected body fluid such as an intracranial fluid. An elongated indicator tube is carried at least in part in a vented chamber which can be mounted so that the indicator tube is in a substantially vertical position. A flexible conduit conveys the selected body fluid from a catheter in the patient to the lower end of the indicator tube. By positioning the indicator tube so that the lower end is level with the in-dwelling end of the catheter, the extent of travel of the body fluid along the tube is a direct indication of the pressure of the body fluid. To provide an upper limit on the pressure the body fluid may attain, at least one opening is provided at a selected position in the wall of the indicator tube inside the chamber. This opening provides an upper pressure limit by permitting fluid to escape from the indicator tube into the chamber when the pressure is sufficient to cause the fluid to reach the opening.