The patient was a 22-year-old woman and suffered from atrial septal defect (ASD) complicated by persistent left superior vena cava (PLSVT). The patient underwent a patch closure using calf pericardium. Despite favorable progress immediately after the operation, fever, enlarged cervical lymph nodes, and leukocytopenia appeared beginning day 8 after the operation. Based on the results of cytodiagnosis of myeloaspiration specimen, the diagnosis of hemophagocytic syndrome (HPS) was made. Since an elevation of 2-5 oligo A synthetase (2-5 AS) levels was observed, the patient was diagnosed to suffer from virus-associated hemophagocytic syndrome (VAHS), and steroid was administered. The patient exhibited a good response to the treatment. The fever declined 3 days after the start of administration. Leukocyte counts were also increased gradually. The patient condition was improved and she was discharged from the hospital on day 28. At present, seven months after the operation, there is no evidence of recurrence and the patient's condition is still monitored.