Abstract: Flow regulator for setting and maintaining a constant flow of blood, blood-substitute, or similar liquid and consisting of a body with a movable part mounted on it and having, first, a bore that serves as a valve housing and accepts the movable part, which serves as a plug, and, second, two connections that communicate more or less at right angles with the bore and have perforations for a flow line and in that the axes of the connections or of their perforations are mutually displaced along the body in such a way that the plug can move in the valve housing only in the vicinity of one perforation from a position allowing complete access to a position ensuring complete closure.