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Background: Hemoglobin (Hb) Chile [β28(B10) Leu > Met; HBB: c.85 C > A] is a rare hemoglobin variant caused by a missense mutation in the HBB gene. Only one case of Hb Chile has been reported worldwide so far. It is an unstable hemoglobin, characterized by cyanosis associated with chronic methemoglobinemia and hemolytic anemia induced by sulfonamides or methylene blue. Case presentation: A 9-year-3-month-old girl had mild anemia of unknown etiology for more than 6 years. She had a slight pallor without other symptoms or signs. The complete blood count revealed normocytic normochromic anemia with a sometimes-elevated reticulocyte count, and the bone marrow cytology showed marked erythroid hyperplasia, but the tests related to hemolysis were normal. Therefore, the whole exome sequencing was performed and showed a heterozygous mutation for HBB: c.85 C > A. With asymptomatic methemoglobinemia confirmed later, she was eventually diagnosed with Hb Chile. Conclusions: This is the first report of Hb Chile in China and the second worldwide. This case shows that Hb Chile is clinically heterogeneous and difficult to diagnose and expands our understanding on the clinical and hematological traits of the disease. [ABSTRACT FROM AUTHOR]