Abstract: An improved apparatus for automatically measuring the viscosity of a sample liquid is disclosed. The apparatus comprises a plurality of viscosimeter tubes mounted in a constant temperature bath, a plurality of vessels adapted for containing the sample liquid, a valve system for controlling the injection and the removal of the sample liquid into and from the viscosimeter tubes and the ascent and descent of the sample liquid in the viscosimeter tubes, a driving circuitry for the valve system, a photosensing device for sensing the meniscus of the liquid at predetermined indication marks of the viscosimeter tubes and a system of measuring the flow time of the sample liquid between two predetermined marks and computing the viscosity of the liquid based on the measured flow time.