A Computerized Ultrasonic Gauging System (CUGS) has been developed to generate a visually useful as well as a quantitative mapping of the outer and inner surfaces of tubes during the various stages of manufacture. Measurements of the outside radius and of the thickness of the tube are performed with a resolution of 0.0025 mm (0.0001 in) as the part is rotating on a lathe with speeds of up to 1000 surface feet per minute. Typically, 500 measurements are made and displayed for each revolution of the part. The transducer is scanned along the axial dimension by the lathe carriage to which it is attached. The axial scan rate is typically 0.25 mm (0.01 inches) per revolution, resulting in very precise topographical maps of all the cylindrical surfaces of the part. The system was developed so that the run-out and the straightness of the part are calculated from the dimensional data obtained. The surface finish of the outside and inside of the part is also available in a post process, color mapped, display, and CUGS is also capable of simultaneously detecting internal flaws in the part. A fluid stream couples the ultrasound to the part, and high speed electronics is employed to perform the measurements. A description of the system is presented with experimental results.