Sulfur mustard (SM), a major potent chemical warfare agent, has been used for its acute toxic effects. Over time, unfortunately, many different long-term health effects of exposure to SM have been detected in humans. There are many available data from soldiers or civilians exposed to SM: testing programs, contaminated workers in factories who were involved with the production of SM, and animal and molecular studies. Today it seems that our data are enough to discuss the carcinogenic effects of exposure to SM-as an alkylating agent-many years after exposure. Herein, we review all available published documents regarding the lung carcinogenicity of SM after both long-term and especially short-term exposure in humans. In summary, it is well documented that SM can cause human lung cancer after long-term exposure, but there has not been strong and definitive evidence for only short-term and acute, single, high-dose exposure until now.