This study was aimed at research on Jeonyak (煎藥) appearing in the bibliography. It was during the Goryeo Dynasty that Jeonyak was first mentioned in literature. At this time, Jeonyak was served for consumption during Palgwanhoe. The ingredients and recipes of Jeonyak were listed for the first time in Suunjapbang, a book written by Kim Yu during the Joseon Dynasty. Since then, they have been found in various books and materials. During the Joseon Dynasty, Jeonyak was made in Neuiwon, a medical administrative organization in the palace, and administered as a seasonal food on Dongji Day in the winter. The king gave various to his guests or subjects as special gifts. As a result, Jeonyak became well known to many people and even to those in foreign countries. Jeonyak is a Korean traditional medicated diet food made from decocted beef-feet, bone stock, and other spices, including jujube paste, honey, ginger, pepper, clove, and cinnamon. Jeonyak has a long 800-year history, and its ingredients and recipes have changed only gradually. Milk was a major ingredient of Jeonyak during the Goryeo Dynasty, but glue and gelatin were added in the Joseon Dynasty. Since then, recipes have mainly used gelatin made from beef-feet, skin, beef-bone, and so on. In conclusion, Jeonyak has an 800-year history as a special medicated diet food (藥膳) served seasonally on Dongji Day in the winter.