This paper reviews the recent research on the physiological role of peptide and protein substances synthesized in boar seminal vesicle glands. Secretions from these glands are the major components of seminal plasma. Unique biochemical properties of seminal vesicle proteins, which determine their numerous functions in the reproductive processes, are discussed. The discovery of phosphotyrosine acid phosphatase in boar seminal vesicle secretions and the first description of the biochemical properties of platelet activating factor acetylhydrolase (PAF-AH) have led to remarkable inroad in molecular andrology. The fundamental role of vesicular low and high molecular antioxidants in the protective function against reactive oxygen species (ROS) is defined. Emphasis is also given to the role of androgens in controlling the secretory activity of boar seminal vesicles.