Methylene blue is utilized as the main treatment of methemoglobinemia. Here we report two cases, in which patient suffered from aniline-induced methemoglobinemia with initial good response but later developed haemolytic anemia due to methylene blue therapy. He was treated with hydration, high flow oxygen and steroid therapy. Caution should be exercised while using methylene blue as antidote of acute methemoglobinemia as both methemoglobinemia and its antidote methylene blue can itself precipitate fatal haemolytic anemia.