The link between the metabolic syndrome (MetS) and skin diseases is increasingly important, with new associations being discovered. The association between MetS and psoriasis or MetS and hidradenitis suppurativa is well known, although the relationship between MetS and various autoimmune or inflammatory diseases has only recently attracted interest. Some inflammatory skin diseases, such as vitiligo, scleredema, recurrent aphthous stomatitis, Behcet disease, rosacea, necrobiosis lipoidica, granuloma annulare, skin tags, knuckle pads, and eruptive xanthomas, have possible associations with MetS. In this review, we examine the state of knowledge involving the relationship between MetS and these dermatologic diseases. (C) 2018 Elsevier Inc. All rights reserved.