Methylene blue is utilized as the main treatment of methemoglobinemia conventionally, but it may be ineffective in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. We report a G6PD-deficient patient who suffered from aniline-induced methemoglobinemia with initial good response Heinz body but hemolytic anemia appeared later 3 d after methylene blue therapy. G6PD deficiency was identified. He recovered uneventfully with hydration, packed blood transfusion and adjuvant luvela-N(dl-alpha-tocopheryl nicotinate) medication. Caution should be taken in using methylene blue as antidote of acute methemoglobinemia, especially when a history of G6PD deficiency is obscure.