Ganoderma lucidum, a macro-fungus, has been used for thousands of years in traditional medicines, especially Chinese traditional medicine, for strengthening body endurance, revitalizing the spleen, and replenishing energy. Recent scientific research on this mushroom has revealed that it contains a highly diverse set of bioactive components. Over 400 bioactive compounds belonging to different classes of biochemicals, including polysaccharides, polypeptides, triterpenoids, enzymes, alkaloids, nucleosides, fatty acids, inorganic elements, steroids, and sterols have been identified from this macro-fungus. Its isolated compounds and crude extracts are reported to have multiple therapeutic effects, including anticancer, antidiabetic, antihypertensive, antimicrobial and immunomodulatory activities. This chapter highlights the ethnomedical uses of Ganoderma lucidum, its isolated bioactive molecules, and biodiscovery potential.