Interfacial Tension (IFT) as the indication of energy at the interface of two immiscible fluids, is a vital parameter for any Enhanced Oil Recovery (EOR) process. The EOR agents such as surfactants, alkaline and polymers tend to reduce the IFT between oil and water to decrease capillary forces and recover more residual oil. Drop shape analysis (pendant drop method) is a convenient way to measure the surface tension. Pendant drop tensiometry, enhanced by video-image analysis, has been considered as a very accurate method for measuring the IFT of fluid/fluid interface for a wide range of IFT values. In this method, the video images of pendant drops are digitized to determine the interface loci, and the IFT are then measured through the solution of the Young-Laplace equation. Wettability of the reservoir rock and interfacial tensions between the reservoir fluids play the most important role on the oil recovery efficiency.