Sulfur mustard (2,2-dichlorodiethyl sulfide, SM) is one of the vesicant classes of chemical warfare agents that causes blistering in the skin and mucous membranes, where it can have lingering long-term effects for up to ten years (1). SM was employed extensively by the Iraqi army against not only Iranian soldiers but also civilians between 1983 and 1988, resulting in over 100,000 chemical casualties. Approximately 45,000 victims are still suffering from long-term effects of exposure (2,3). More than 90% of the patients exposed to SM exhibit various cutaneous lesions in the affected area. The human skin can absorb approximately 20% of the SM through exposure. Up to 70% of the chemical is concentrated in the epidermis and the remainder in the basement membrane and in the dermis (4).Sulfur mustard exists in different physical states. The liquid form of SM evaporates slowly in cold weather and can penetrate through the clothing, thereby increasing exposure. However, the gas form readily diffuses in the air and it can be inhaled, leading to systemic absorption. In addition, warm temperatures are ideal conditions that liquid SM present in the clothing of the exposed individual could be converted to gas form. SM-induced clinical cutaneous symptoms include itching and burning. Other clinical findings include erythema or painless sunburn, bulla, hypo- and hyper pigmentation in both exposed and unexposed areas (5,6) The mechanism and biochemical cascade of SM-induced cutaneous manifestations are not completely understood but several published pathways support many of the know facts. Our current understanding fails to explain the time interval between the acute chemical exposure and the late-onset and delayed tissue damage (7,8). The aim of this article is to review the acute and long-term cutaneous findings resulting from SM exposure. Also, cellular and molecular mechanism involved in SM-induced skin pathology have been discussed.