This study was aimed to investigate the expression of ICAM-1 (CD54) in pediatric tumor and acute leukemia (AL), so as to understand the distribution of ICAM-1 and its clinical significance. The expression of ICAM-1 in tissues of 46 pediatric tumor patients were detected by immunohistochemistry, and in bone marrow cells of 60 pediatric acute leukemia (AL) patients were detected by flow cytometry. 46 pediatric tumor patients included 10 lymphoma, 3 hepatoblastoma, 6 neuroblastoma, 2 rhabdomyosarcoma, 6 Ewing's bone sarcoma, 2 fibrosarcoma, 5 primitive neuroectodermal tumor, 11 nephroblastoma and 1 osteosarcoma. 60 AL pediatric patients included 20 acute lymphocytic leukemia (ALL) patients and 40 acute nonlymphocytic leukemia (ANLL) patients containing 20 M1, M2, M3 patients and 20 M4, M5. The results indicated that expression of ICAM-1 was more positive in all 3 hepatoblastoma cases, which represent a higher positive rate than that in lymphoma, neuroblastoma, rhabdomyosarcoma, Ewing's sarcoma of bone and osteosarcoma. However, no expression of ICAM-1 was observed in fibrosarcoma, nephroblastoma and primitive neuroectodermal tumor patients. On the other hand, the expression rate of ICAM-1 was 55 in ALL, 65 in ANLL M1, M2, M3, and 50 in ANLL M4, M5. It is concluded that the expression of ICAM-1 in pediatric tumor and AL has variability. The ICAM-1 positive expression is observed in hepatoblastoma and ANLL M1, M2, M3 patients, whereas it is undetectable in fibrosarcoma, nephroblastoma and primitive neuroectodermal tumor patients.