Gyeongoggo is first described in the Collected Prescription by Hong Family in the Song Dynasty in China. It is composed of Radix Rehmnniae, Panax ginseng, Poria cocos, and Mel. Its main efficacy is to treat weakness of primordial essence of body and dry cough, and to invigorate qi and replenish yin principle. It is one of the most important prescriptions that people have been using for a long time. We studied the documents recorded in the medical classics and comprehended the following results. Gyeongoggo has efficacy to keep a person healthy and live long age, to treat amnesia and dizziness from brain weakness, to strengthen muscle and bone by improving function of stomach and colon, to improve a person`s memory and judgement, to invigorate brain weakness, and, to treat tuberculosis and lung cancer. The longer a person take it, the better it is for one`s health and meditation. When it is made, it is important to mix four components up, to boil it with an oak tree for three days and nights, and then to add water from a well to reduce heat for a full day, and to boil up again for a full day to mature fully. As gyeongoggo is acquired not only by the full heart of a manufacturer but also the sympathy of nature, it is important to choose a clean place to make and keep. When it is taken, it is proper to take it with warm water or liquors. And when it is made, we came to know that it is possible to make gyeongoggo with special efficacy by adding one to three more components.