ABSTRACTObjective:The objectives of this study were to describe the first pediatric case of cold agglutinin syndrome (CAS) triggered by human adenovirus and review the literature.Case description:This case report involves a previously healthy, 2½-year-old female child with human adenovirus isolated in a nasal swab. At 72 h after admission, the patient progressed to a severe episode of anemia (hemoglobin level: 2.6 g/dL). The laboratory findings were consistent with CAS. The patient received blood transfusion, vitamin supplementation, adequate hydration, and thermal protection. At her last follow-up, 1 year after her initial presentation, she remains clinically well without signs of hemolysis.Comments:While severe CAS is extremely uncommon in the pediatric emergency department, human adenovirus infection is a common illness in pediatrics. Recently, the adenovirus has been associated with new complications (acute hepatitis and fulminant liver failure). Pediatric physicians and hematologists should be aware of unusual evolution, signs, and symptoms of this infection that warrant more urgent medical attention. In this case, the hematologic complication suspicion was the key to early diagnosis and adequate management.