The skin is an endocrine organ with the expression of metabolizing enzymes and hormone receptors for diverse hormones. The sebaceous gland is the main site of hormone biosynthesis, especially for androgens, and acne is the classical androgen-mediated dermatosis. In sebocytes, conversion of 17-hydroxyprogesterone directly to dihydrotestosterone bypassing testosterone has been demonstrated, while type II 17 beta-hydroxysteroid dehydrogenase can inactivate the action of testosterone and dihydrotestosterone. The androgen receptor-dependent genomic effect of dihydrotestosterone on sebocytes is confirmed. Further evidence supports the PI3 K/Akt/FoxO1/mTOR signaling in the involvement of the interplay between androgens, insulin, insulin-like growth factor, and hyperglycemic diet in acne. Androgens not only regulate embryology and lipogenesis/sebum synthesis in sebocytes but also influence inflammation in acne. Genetic studies indicate that regulation of the androgen receptor is an important factor in severe acne. Further studies are required to understand the effect of estrogen and progesterone on sebaceous gland and comedogenesis, considering the change of acne in pregnancy and postmenopausal acne. Special attention should be paid to nonobese patients with polycystic ovarian syndrome and hyperandrogenism-insulin resistance-acanthosis nigricans syndrome. In spite of extensive gynecologic experience in the use of combined oral contraceptives for acne, evidence based on dermatologic observation should be intensified. (C) 2017 Elsevier Inc. All rights reserved.