Medical treatment of male infertility can be divided into two categories – targeted therapy to a known cause of infertility and empirical treatment. The most common reason to use targeted therapy is to treat hypoandrogenism. Primary hypoandrogenism (steroidogenic dysfunction) is defined as a low serum testosterone level with compensatory elevated luteinizing hormone (LH) level. Secondary hypoandrogenism (pituitary dysfunction) can be categorized further into congenital forms, such as idiopathic hypogonadotropic hypoandrogenism, or acquired forms and is characterized by low serum testosterone level associated with a low LH level relative to serum testosterone level. Other medical indications for targeted therapy are infections, inflammation, antisperm antibodies, and retrograde ejaculation, all of which are discussed elsewhere in this book. Empirical treatment is defined as treatment that relies on experience or observation alone, without due regard for system and theory, and it is routinely used in the treatment of males with idiopathic infertility or with an uncorrectable cause of their infertility.