Objectives : This study was to analyze the definitions of herbs, herbal drugs, crude drugs and natural products in the relevant laws and regulations, understand the related problems, and propose directions for improvement. Methods : I analyzed the legal definitions in respect of herbs, herbal drugs, crude drugs and natural products in relevant laws and regulations since 1945, explained the problems, and suggested the solution-considering the academic stance of Traditional Korean Medicine and the dualistic medical and pharmaceutical system. Results : Herbs are defined as "refined things that are cut and dried in their most original state". The definition of crude drugs includes herbs and the "cell contents, secretion, extracts, minerals and other parts of animals and plants that are used medicinally". The concept of natural products is expanded to adding tissue cultures to the definition of crude drugs. Conclusions : The definition of herbs should at least include all products that are "processed, extracted and prepared" as well as contents that consist of various forms of hospital-prepared herbs. The term "herbal drug" corresponds to a traditional term of "drug", and this should be established as a concept to explain "drugs in raw materials that are used to prepare herbs and/or manufacture herbal medicine". The legal definition of herbs should include the concept of crude drugs. Herbal drug preparations and crude drugs should be included in the definition of herbal drugs.