Since the elderly population has been increasing recently in our country, old male patients with testosterone deficiency syndrome (TDS) with a significantly decreasing quality of life are becoming increasingly common. TDS in males is defined as a biochemical syndrome associated with advancing age and characterized by clinical manifestation and a deficiency in the serum testosterone level. These patients should be treated with extrinsic testosterone to improve quality of life. TDS in males should be diagnosed in the case of clinical manifestation with serum total testosterone <8 nmol/L (230 ng/dL) or calculated free testosterone <225 pmol/L (65 pg/mL) but not diagnosed in the case of serum total testosterone >12 nmol/L (350 ng/dL). Products for testosterone replacement therapy (TRT) are administrated orally, transdermally, and through injectable preparations. Daily testosterone undecanoate is widely used for oral administration with good results and no hepatotoxicity. Short-acting intramuscular preparations are very effective but show wide swings in the resulting supra-physiological level of serum testosterone. Long-acting intramuscular preparations is also very effective and lasting for 3 months with normal physiologic levels. Many products for TRT on the market are effective and generally safe. However, those have a few significant adverse events each other. The ideal product should have notable effectsand few side effects, (such as selective androgen receptor modulators), be easy to administrate, maintain physiologic serum concentration, and be inexpensive. TDS in males can easily be correct by TRT. However, the advantages and disadvantages of the individual products and follow-up management of complicated adverse events should be understood before starting and maintaining TRT.