A 42-y-old female presented with common cold-like symptoms. Laboratory data showed mild liver dysfunction together with peripheral blood eosinophilia. She was suspected of having a helminthic infection, however parasite eggs or larvae were not detected by repeated stool examinations. Eventually she transpired to have a high IgG antibody titer against excretory-secretary (ES) antigen of Ascaris suum larvae, but not of Toxocara canis larvae, suggesting that she had been suffering from visceral larva migrans (VLM) caused by A. suum. Her sickness improved without any treatment. Current results clearly highlight the usefulness of ES antigens derived from larvae of A. suum for the fine discrimination of VLM caused by A. suum and by T. canis. Application of A. suum derived ES antigens as a diagnostic tool may reveal the distinctive clinical features of VLM caused by A. suum.