Objectives : The objectives of this study lie in theoretical establishment of Bopyeo-tang for treating asthenic syndrome of the lung through analyzing the component medicines and combination principles of Hyeongok's Bopyeo-tang, and furthermore, maximizing the clinical effectiveness of Bopyeo-tang. Methods : This study analyzed the component medicines and combination principles of Hyeongok's Bopyeo-tang based on the theory for properties and tastes of herbal medicines from the ${\ulcorner}$Yellow Emperor's Canon of Internal Medicine${\lrcorner}$, the theory for principal herbal medicine, assistant herbal medicine, adjuvant herbal medicine, dispatcher herbal medicine, and the five elements doctrine. Hyeongok's Bopyeo-tang is an unusual prescription, composed of 7 kinds of ingredients. Results : There are three methods for curing asthenic syndrome of the lung according to the five elements doctrine: invigorating the lung, invigorating the spleen and purging the heart. There are two available methods to invigorate the lung, taste and property invigoration, according to the theory for properties and tastes of herbal medicines. They each imply the sour taste and the cool property invigorate the lung. In the case of taste invigoration, two herbal medicines with sour taste, Sarcucarpium Corni and Fructus Schisandrae, are combined into the principal and assistant herbal medicine, respectively. For property invigoration, two herbal medicines with the cool property, Colla Corii Asini and Radix Ophiopogonis, are combined into adjuvant herbal medicines. There are likewise two methods to invigorate the spleen, including taste and property invigoration according to the theory for properties and tastes of herbal medicines. They each mean the sweet taste and the warm property invigorate the spleen. Therefore, it is important to use sweet herbal medicines for taste invigoration and warm ones for property invigoration. Both sweet and warm herbal medicines, Radix Ginseng and Rhizoma Atractylodis Macrocephalae, are combined into adjuvant herbal medicines. Lastly, there are two methods to purge the heart, which include taste and property purgation according to the theory for properties and tastes of herbal medicines. Taste purgation means to purge the heart with sweet taste and property purgation to purge the heart with cold property. Therefore, it is important to use sweet herbal medicines for taste purgation and cold ones for property purgation. Both sweet and cold herbal medicines, Colla Corii Asini and Radix Ophiopogonis, were combined to purge the heart and invigorate the lung. In addition, Radix Glycyrrhizae Praeparata is added as a dispatcher herbal medicine, harmonizing all the other herbal medicines comprising the formula. Conclusions : First, to treat asthenic syndrome of the lung, the methods of invigorating the lung and the spleen and purging the heart 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, and dispatcher herbal medicine. As a good example, Hyeongok's Bopyeo-tang is combined according to the above theories. In conclusion, this formula was created by applying the theory of properties and tastes of herbal medicines.