AIM: To investigate the expression of vascular endothelial growth factor (VEGF) and microvascular density (MVD) count in pediatric malignant liver tumor and their clinical significances. METHODS: Fourteen children with malignant liver tumors including seven hepatocellular carcinomas (HCCs), five hepatoblastomas, one malignant mesenchymoma and one rhabdomyosarcoma were studied. Twelve adult HCC samples served as control group. All samples were examined with streptavidin-biotin peroxidase (SP) immunohistochemical staining for VEGF expression and MVD count. RESULTS: VEGF positive expression in all pediatric malignant liver tumors was significantly higher than that in adult HCC (0.4971±0.14 vs0.4027±0.03, P<0.05). VEGF expression in pediatric HCC group was also markedly higher than that in adult HCC group (0.5665±0.10 vs0.4027±0.03, P<0.01) and pediatric non-HCC group (0.5665±0.10 vs 0.4276±0.15, P<0.05). The mean value of MVD in pediatric malignant liver tumors was significantly higher than that in adult HCC (33.66±12.24 vs 26.52±4.38, P<0.05). Furthermore, MVD in pediatric HCC group was significantly higher compared to that in adult HCC group (36.94±9.28 vs 26.52±4.38, P<0.05), but there was no significant difference compared to the pediatric non-HCC group (36.94±9.28 vs 30.37±14.61, P>0.05). All 7 children in HCC group died within 2 years, whereas the prognosis in pediatric non-HCC group was better, in which two patients survived more than 5 years. CONCLUSION: Children with malignant liver tumors, especially with HCC, may have extensive angiogenesis that induces a rapid tumor growth and leads to a poor prognosis. AIM: To investigate the expression of vascular endothelial growth factor (VEGF) and microvascular density (MVD) count in pediatric malignant liver tumor and their clinical significances. METHODS: Fourteen children with malignant liver tumors including seven hepatocellular carcinomas (HCCs) All samples were examined with streptavidin-biotin peroxidase (SP) immunohistochemical staining for VEGF expression and MVD count. RESULTS: VEGF positive expression in all pediatric malignant liver tumors was significantly higher than that in adult HCC (0.4971 ± 0.14 vs. 0.4027 ± 0.03, P <0.05). VEGF expression in pediatric HCC group was also markedly higher than that in adult HCC group (0.5665 ± 0.10 vs 0.4027 ± 0.03, P <0.01) and pediatric non-HCC group (0.5665 ± 0.10 vs 0.4276 ± 0.15, P <0.05). The mean value of MVD in pediatric malignant liver tumors was significantly hig MVD in pediatric HCC group was significantly higher than that in adult HCC group (36.94 ± 9.28 vs 26.52 ± 4.38, P <0.05) , there was no significant difference compared to the pediatric non-HCC group (36.94 ± 9.28 vs 30.37 ± 14.61, P> 0.05). All 7 children in HCC group died within 2 years, while the prognosis in pediatric non-HCC group was better, in which two patients survived more than 5 years. CONCLUSION: Children with malignant liver tumors, especially with HCC, may have extensive angiogenesis that induces a rapid tumor growth and leads to a poor prognosis.