Background and Objectives : There are three kinds of formulas for purging the kidney to cure its sthenic syndrome based on the types of preparation formulas : Sashintang, Sashinhwan and Sashinsan. There are 4 kinds of Sashintang, 1 kind of Sashinhwan and 1 kind of Sashinsan. Combination of herbal medicines, carried out in formulas for purging the kidney, consists of various kinds depending on medical scientists' personal experience in medical treatment without any general principles, which makes it difficult to apply it to clinical use. The objectives of this study lie in theoretical establishment of Pyeongshintang for curing the sthenic syndrome of kidney through analyzing the component medicines and combination principles of Hyeongok's Pyeongshintang, and furthermore, maximizing the clinical use of Pyeongshintang. Methods : This study analyzed the component medicines and combination principles of Hyeongok's Pyeongshintang based on the theory for properties and tastes of herbal medicines from the "Yellow Emperor's Canon of Internal Medicine", the theory for principal herbal medicine, assistant herbal medicine, adjuvant herbal medicine, dispatcher herbal medicine, and the five elements doctrine. Hyeongok's Pyeongshintang is an odd prescription, composed of 7 kinds of ingredients : No.1 Rhizoma Alismatis (2don;7.5g), No.2 Poria (1don;3.75g), No.3 Radix Paeoniae Alba (1don), No.4 Fructus Chaenomelis (1don), No.5 Polyporus (1don), No.6 Cortex Cinnamomi (1don), and No.7 Radix Glycyrrhizae (1don) Results : There are three methods for curing the sthenic syndrome of kidney according to the five elements doctrine : purging the kidney, purging the liver and invigorating the spleen. First, if you suffer from the sthenic syndrome of the kidney, you need to purge your kidney. There are two available methods, including taste and property purgation according to the theory for properties and tastes of herbal medicines. They each imply the salty taste and the hot property purge the kidney. In the case of taste purgation, two herbal medicines with salty taste, Rhizoma Alismatis and Poria, are combined into the principal and assistant herbal medicine, respectively. For property purgation, two herbal medicines with the hot property, Polyporus and Cortex Cinnamomi, are combined into adjuvant herbal medicines. Secondly, if you suffer from the sthenic syndrome of the kidney, you need to purge your liver which is child in the mother-child relationship in inter-promotion among the five elements. There are two methods to purge the liver, including taste and property purgation according to the theory for properties and tastes of herbal medicines. They each mean the sour taste and the cool property purge the liver. Therefore, it is important to use sour herbal medicines for taste purgation and cool ones for property purgation. Both sour and cool herbal medicines, Radix Paeoniae Alba and Fructus Chaenomelis, are combined into adjuvant herbal medicines. Lastly, if you suffer from the sthenic syndrome of the kidney, you need to invigorate your spleen which is an element being surpassed in the relationship between the elements surpassed and ones not surpassed in inter-restraint among the five elements. There are two methods to invigorate the spleen, which include taste and property invigoration according to the theory for properties and tastes of herbal medicines. Taste invigoration means to invigorate the spleen with sweet taste and property invigoration to invigorate the spleen with warm property. Therefore, it is important to use sweet herbal medicines for taste invigoration and warm ones for property invigoration. Both sweet and warm herbal medicines, Polyporus and Cortex Cinnamomi, were combined to invigorate the spleen and purge the kidney. In addition, Radix Glycyrrhizae are combined as dispatcher herbal medicine, harmonizing all the herbal medicines composing the formula. Conclusions : First, to cure the sthenic syndrome of the kidney, the methods of purging the kidney and the liver, and invigorating the spleen should be used according to the five elements doctrine. Secondly, herbal medicines appropriate for those treatment methods should be chosen according to the theory for properties and tastes of herbal medicine and thirdly, the combination of those herbal medicines should be carried out according to the theory for principal herbal medicine, assistant herbal medicine, adjuvant herbal medicine, dispatcher herbal medicine. As a good example, Hyeongok's Pyeongshintang is combined according to the above theories. In conclusion, this formula was created by applying to the theory for properties and tastes of herbal medicines.