This chapter reviews the high-pressure effect on the endogenous enzymes found separately in (mammal) meat, fish, and eggs. The chapter is divided into three sections covering the enzymes important for lipolysis, proteolysis, lipid oxidation, or other activities in each of these food types. Each section starts with a short presentation of the enzymes of relevance, followed by a review of the main results found in the scientific literature. This review shows that although no general conclusion on the relationship between pressure-induced enzyme modification and enzyme activity may be drawn, considerable scientific knowledge is available, providing a solid basis for further investigations and potential practical uses of HP processing of meat, fish, and eggs.