The purpose of reporting this series of patients is to illustrate the role of ascorbic acid in the treatment of severe acquired methemoglobinemia (metHb), especially when methylene blue is not available. Medical records of affected patients were reviewed to collect history of exposures, food ingestion, physical examination, pulse oximetry, blood gas, and co-oximetry results, and outcomes. Five cases of acquired metHb are presented here, all of whom received treatment with ascorbic acid and fully recovered after 24 hours of treatment. Our series emphasizes that ascorbic acid is an effective alternative in the management of acquired metHb if methylene blue is unavailable and suggests that ascorbic acid infusion may be indicated in patients with glucose-6-phosphatase dehydrogenase deficiency.