Sulfur mustard (SM) or mustard gas is a chemical weapon which for the first time was employed during world war I; later on it was used by Iraqi military forces against Iranian army and civilians (1980-88). This agent injured over 100000 Iranians and one-third of them are still suffering from its complications. SM is an alkylating agent with cytotoxic, mutagenic and vesicating properties, which targets the skin, eyes and respiratory systems. In this study we review the acute and chronic effects of SM on the skin. We obtained information of this paper from a search of PubMed. Google, Iran Medex, Irandoc and SID until beginning of 2011. The most common acute effects of SM on skin were: pruritus and burning (26%-96.8%), pain (25%-77.4%), erythema (20.6%-83.9%), hyperpigmentation (20%-83.9%), and vesicle and bulla (15.4%-80.6%). The most common chronic effects were: pruritus (24.7%-94.7%), burning (9.9%-52.1%), scar (4.5%-70%), hyperpigmentation (5.9%-55%), hypopigmentation (3.2%-40%), xerosis (2.1%-43.7%) and cherry angioma (12.2%-70.5%). After passing more than 20 years of the end of the Iraq-Iran war, the victims still suffer from many skin complications of SM and some of them such as itching and dry skin have negative effects on the performance and quality of their life. Up to now, serious skin complications like malignant skin tumors have been rare and a longer time may be required to establish. Therefore further follow-up is needed to detect and treat any kind of skin cancers promptly.