The anatomy and physiology of male sexual functions form the foundation for understanding male sexual dysfunction (MSD). This chapter explores the structural and functional aspects of the male reproductive system, including the scrotum, testes, epididymis, vas deferens, seminal vesicles, prostate, bulbourethral glands, and the penis. It discusses key physiological processes such as spermatogenesis, androgen production, testicular thermoregulation, and the neurovascular mechanisms underlying erection, ejaculation, and detumescence. Special emphasis is placed on the roles of the hypothalamic–pituitary–gonadal axis, penile vascular dynamics, and neural regulation in sexual response. By linking normal anatomy and physiology with the pathophysiology of conditions—such as erectile dysfunction, premature ejaculation, and reduced libido—this chapter not only provides a comprehensive basis for understanding male sexual health and dysfunction, but it also equips readers with practical knowledge for clinical application.