Methylene blue is used to check tubal patency during laparoscopy. We report the case of a 28-year-old patient who presented a blue coloring of the skin, mucous membranes and nails after methylene blue test during laparoscopy for infertility. The oxygen saturation was 82%. The patient was hospitalized for 48 hours in the intensive care unit and spectrophotometric analysis revealed a methemoglobin level of 8.9%, thus confirming the diagnosis of methemoglobinemia. The suites were simple with normalization of the saturation. It is important to know the complications of the injection of methylene blue in order to prevent them and ensure adequate monitoring for the patients.