Background: Sulfur mustard (2,2’-bis-chloroethyl-sulfide; SM) has been a military threat since the World War I. SM is the major chemical warfare agent used byJapanduring World War II. The clinical picture of poisoning, including cutaneous blisters, respiratory tract damage, ocular lesions and bone marrow depression is well known. In this report, we describe a civilian exposure in August 2003, in Qiqihar, Northeast China’s Heilongjiang Province. Aim: To describe the clinical features and treatment of sulfur mustard toxicity. Results: In 44 victims of SM exposure, 32 had ocular symptoms; 43 showed significant skin blistering and pigmentation; 15 had pulmonary symptoms such as productive cough occurred; 18 have Central nervous symptoms and other effects. Conclusion: The 44 victims were all injured, when five barrels of mustard gas were dug up at a construction site inQiqihar. The gas leak killed one and injured 43 others, one of the worst accidents involving chemical weapons abandoned by Japanese invading troops in China after WWII.