Inflammation is caused by a variety of stimuli including physical damage, UV irradiation, microbial invasion, and immune reactions. The classical key features of inflammation are redness, warmth, swelling, and pain, and their cascades can lead to the inflammatory bowel disease and psoriasis. Many inflammatory diseases are becoming common among the elderly worldwide. Clinically used anti-inflammatory drugs suffer from the disadvantages of side effects and high treatment costs in the case of biologics. Therefore, research on new anti-inflammatory molecules and the elucidation of their molecular mechanisms are being actively conducted. This Special Issue on "Chemopreventive Activities of Phytochemicals" is intended to offer anti-inflammatory active natural products as candidates and/or leads for pharmaceuticals. The research fields of this Special Issue include natural products, chemistry, phytochemistry, pharmacognosy, food chemistry, bioorganic synthetic chemistry, chemical biology, molecular biology, molecular pharmacology, and other related research fields.