Three cases of toxic methemoglobinemia resulted from absorption of nitrate salts through burned skin areas. In addition to the unusual route of intoxication, this report emphasizes the occupational hazard of methemoglobinemia in workers exposed to nitrogen salts and the importance of rapid diagnosis and treatment. The diagnosis of methemoglobinemia should be suspected in any case of cyanosis refractory to oxygen therapy. Appropriate treatment should include oxygen, methylene blue, and exchange transfusion in clinically severe cases.