Abstract Vancomycin is a first-line drug for treating methicillin-resistant Staphylococcus aureus. Thrombocytopenia is a rare adverse reaction to vancomycin treatment, and there are no reports of vancomycin-induced thrombocytopenia (VIT) in infants. We describe the case of a 3-month-old girl who was diagnosed with purulent meningitis. After 13 days of treatment with vancomycin, her platelet count reduced to 8 × 109/L. Vancomycin was discontinued, and intravenous methylprednisolone was administered. The platelet count returned to normal after 4 days. Patients, especially young children, receiving vancomycin for a long clinical course should undergo careful monitoring of laboratory indicators and blood tests.