Clear cell sarcoma (CCS), a rare malignant tumor with a predilection for young adults, is of poor prognosis. Recently however, boron neutron capture therapy (BNCT) with the use of p-borono-L-phenylalanine (BPA) for malignant melanoma has provided good results. CCS also produces melanin; therefore, the uptake of BPA is the key to the application of BNCT to CCS. We describe, for the first time, the high accumulation of boron in CCS and the CCS tumor-bearing animal model generated for BNCT studies. (c) 2011 Elsevier Ltd. All rights reserved.