Publisher Summary This chapter discusses the biosynthesis of microbodies, such as peroxisomes and glyoxysomes. With respect to biochemical properties, microbodies are characterized by at least one oxidase reducing O 2 to H 2 O 2 . This production of peroxide and its employment by catalase-catalyzed reactions led to the term “peroxisome.” Ribosomes are not associated directly with the peroxisome membranes. RNA may be bound in some indirect way to plant microbodies that are at the stage of fat mobilization. In vivo studies provide the insights into the essential steps of organelle biosynthesis, such as the site of protein synthesis, the sequence of intermediary pools, and the form of final arrangement of proteins within the organelle. Some of the many steps between gene activation, mRNA processing, translation, and import and assembly can be examined in vitro . The chapter discusses the pathway of microbody biosynthesis with reference to the kind of cell in which these organelles function.