Xerosis (dry skin) is defined as dehydration of stratum corneum and characterized by scales, fissures, erosion, and calluses on the skin, which thereby impairs the skin barrier function. In addition, most xerosis patients exhibit uncomfortable itching feelings or pain. Thus, structural and functional improvement of the impaired skin barrier may facilitate a treatment for xerosis and improve the quality of life of patients. On the other hand, sebum secreted from sebaceous glands plays an important role for maintaining physiological functions by forming a biological barrier on the skin. Since we found novel evidence that an ethanol extract of Grifola frondosa (Maitake mushroom) fruiting body, which is termed Gripin®, augments the sebum production in hamster sebocytes in vivo and in vitro, the Maitake extract might be an effective means of treating xerosis. In the present study, we performed a clinical trial investigation using a cream containing 0.2% Maitake ethanol extract (Maitake cream) (舞潤®, MaiJun) (Fig. 1) on the posterior antebrachial and crural skin of 60 patients with moderate to severe xerosis, and on the posterior antebrachial skin of healthy volunteers.