Throughout human history, natural products—including terrestrial plants, animal products, marine organisms, and products of microorganismal fermentation—have been used in traditional medicines. This historical experience with natural products as therapeutic agents has evolved to sophisticated isolation of active chemical entities from ethnopharmacological plants with the effect that, in modern medicine, natural products are increasingly the primary sources in early drug discovery. The population is aging in many modern societies and is linked to steadily increasing morbidity rates of cancer and cerebrovascular disease, thus mandating the importance of better preventive as well as therapeutic options. Many medically advanced societies are exploring the adjunctive use of western and oriental medicine alternatives, enhancing the demand for natural products. While evidence-based data is still scant in the field of alternative medicines, in this special issue we have the pleasure of sharing with our readers many scientific articles on natural products with potential medicinal use. This special issue contains 6 review articles and 19 original peer-reviewed papers. The reviews included summarize such diverse topics as the biological and pharmacological effects of ginsenoside Rb1, isolated from red ginseng root, on skin damage (Y. Kimura et al.); tumor suppression in animals by a fruit pulp containing high amounts of β-cryptoxanthin and hesperidin (T. Tanaka et al.); the favorable effects of purple corn flower in treatment of infectious diseases (J. B. Hudson); the biomechanisms and clinical outcome of Rhus verniciflia extract in patients (W. Choi et al.); the safety of cruciferous plant extracts (O. Scott et al.); and the antitumor activity of artemisinin and its analogs (M. P. Crespo-Ortiz and M. Q. Wei). The original articles embrace a wide variety of topics, such as apoptosis, suppression of cell proliferation and tumorigenesis (Y. Hu et al., H. Kurose et al., A. Lerner et al., Booth et al., Kita et al., Mohd et al., and G. M. Geetha et al.), the antibacterial/antifungal/anti-inflammation/antioxidative characteristics of natural extracts (E. Biazar et al., Y.-S. Lee et al., Y. Hu et al., A. Cha et al., H. Sun et al., and P.-F. Kao et al.), cardiovascular activity of specific natural products (K. Awang et al.), the effects of extracts on blood parameter levels in diabetic patients (T. Klangjareonchai and C. Roongpisuthipong), examination of isolation techniques (N. A. Mahyudin et al.), enzymatic activity (B. Elya et al.) and metabolism of certain extracts (Y. Shimoda et al.); and specific effects of some natural products on aryl hydrocarbon receptor expression (H. M. Korashy et al.). We would like to thank the authors for their timely contributions. Finally, we also thank all reviewers for their hard work questioning, pruning, and refining these articles. Masa-Aki Shibata Ikhlas A. Khan Munekazu Iinuma Tomoyuki Shirai