Background: Despite the significant improvements of long-term survival rates for pediatric cancers, prognosis of refractory/relapsed solid tumors are extremely poor, and novel strategies are desired. Recently, tumor immunotherapies such as anti-PD-1/PD-L1 antibodies have been recognized as an effective option for many intractable cancers. However, there are still a substantial number of patients who do not show objective responses to the PD-1/ PL-L1 blockades. On the other hand, like PD-1/PD-L1, other immune checkpoint pathways such as TIM3/GAL9, LAG3/MHC-II, and BTLA/HVEM have been reported to regulate immune responses in tumor microenvironment. Although these pathways could be alternative targets for novel immune therapies, almost no information is available whether pediatric solid tumors express these molecules. Herein, we characterized the expression of various checkpoint proteins, and tumor infiltrating lymphocytes (TILs) in tumor specimens from untreated children with common pediatric solid tumors. Methods: Sections cut from formalin-fixed, paraffin-embedded tissue blocks were processed and evaluated for GAL9, MHC-II, and HVEM on tumor cells, and TIM3, LAG3, and BTLA on TILs by immunohistochemistry. Results: Specimens from 65 patients, including 16 neuroblastomas, 11 rhabdomyosarcomas, 12 osteosarcomas, 10 hepatoblastomas, 10 Wilms tumors, and 6 Ewing sarcomas were evaluated. Although in neuroblastoma and Ewing sarcoma, checkpoint proteins on the tumor were rarely detected, 64% of the patients with rhabdomyosarcoma and 83% with osteosarcoma expressed moderate to high levels of HVEM. TILs were detected in all tumor types among which CD8 positive T cells were the most dominant population following CD4 positive T cells. Interestingly, in rhabdomyosarcoma, and osteosarcoma, more than 70% of the TILs expressed moderate to high levels of BTLA. Conclusions: A subset of pediatric solid tumors demonstrated tumor associated checkpoint expressions, and TILs also expressed corresponding ligands of the checkpoints, which suggested immunogenic environments may be created, and the checkpoint blockades could induce favorable immune responses.