Methemoglobinemia is an uncommon, often overlooked, and potentially reversible cause of hypoxia in the perioperative setting. Methemoglobinemia occurs when the bound ferrous iron (Fe2?) of oxyhemoglobin is oxidized to the bound ferric iron (Fe3?) of methemoglobin. An indication of methemoglobinemia is a discrepancy between the transcutaneous oxygen saturation (SpO2) and the calculated arterial oxygen saturation on arterial blood gas (SaO2). Patients with lifelong congenital methemoglobinemia or with a history of chronic methemoglobinemia secondary to chronic exposure to drugs or toxins, methemoglobin levels can be as high as 40% and still be well tolerated with cyanosis (blueish cast to the mucous membranes of the skin) being the only presenting manifestation. No reports with regards to the effect of methemoglobin during pre-operative, intra-operative or post-operative period have been described and the effect of bone healing in methemoglobin patient have not been described in literature. It mimics covid like illness with decreased saturation, at presentation resulting in being not fit for surgery however after thorough investigation it was diagnosed to be methemoglobinemia.