A 7-year-old girl was diagnosed with alveolar rhabdomyosarcomas of the right crural region. The patient was initially treated with chemotherapy and surgery with wide surgical margins, with radiotherapy. The tumors relapsed in the popliteal region surrounding the popliteal vessels. The patient received sentinel lymph node biopsy for a recurrent tumor using isosulfan blue dye, with the "sentinel node" being malignant-negative, and a "nonsentinel node" positive. Sentinel lymph node biopsy with conventional blue dye alone might be insufficient to assess lymph node status in patients with recurrent rhabdomyosarcoma previously treated with surgery and/or radiotherapy.