Proteinases and their inhibitors are ubiquitous in all living organisms and play crucial roles in various biological and physiological processes. Proteinases are part of several proteolytic cascades that are key components of the innate immune system of shrimps and serve important roles in several related biochemical pathways, such as those involved in apoptosis and melanization. Protease inhibitors, on the other hand, precisely regulate the pathway in order to prevent excessive activation of cascades and prevent consequent damage to host tissue. Moreover, host proteinase inhibitors also function in the inhibition and clearance the proteases of invading microorganisms. In shrimps, several proteinases and proteinase inhibitors have been reported that are linked to the immune system