Pectinases constitute a group of enzymes widely used by the fruit and textile industries. Besides these industrial applications, these enzymes play an important biological role in protoplast fusion technology and plant pathology. Since the applications of pectinases in various fields are widening are becoming wider, it is important to understand the nature and properties of these enzymes for an efficient and effective application. For the past few years, intensive research has been carried out on isolation and characterization of pectinases. They are a group of enzymes that contribute to the degradation of pectin by various mechanisms and can be classified as esterases, eliminative depolymerases (lyases) and hydrolytic depolymerases (polygalacturonases). This chapter will describe the current state of knowledge of the main assays used to quantify pectinolytic enzymes and their activity.