The existence of specific immunity against pediatric tumors is not well studied. We report here the CD3+CD4-CD8+ cytotoxic T lymphocyte (CTL) line established from tumor-infiltrating lymphocytes (TIL) of a 3-mo-old child with Wilms' tumor. This CD3+CD4-CD8+ CTL line showed cytotoxicity against the HLA-A2402+ tumor cells including the autologous tumor, adenocarcinomas from various organs (colon, stomach, lung, and ovary), and an esophageal squamous cell carcinoma. No other cell lines examined, including HLA-A2402- tumors, K562 cells, or HLA-A2402+ normal cells were lysed by this CTL line. This CTL line recognized an HLA-A2402- ovarian adenocarcinoma transfected with HLA-A2402 cDNA. These results suggest the existence of HLA-A2402-restricted and tumor-specific CTL at the tumor site of a child with Wilms' tumor.