Abstract: Fifty one patients (27 boys and 24 girls) with solid tumors whose ages ranged between 2 and 168 months were enrolled. Serum Vascular endothelial growth factor by Sandwich Enzyme linked immunosorbent assay was determined for all patients before any treatment and for 17 patients of them while in remission 6-9 months post therapy. Tissue biopsy was obtained for micro vessel count (MVC) determination by staining endothelial cells for factor VIII-related antigen with the use of a standard immunoperoxidase technique. Before therapy, median concentration of serum VEGF was significantly increased in solid tumors` patients when compared to control group (p<0.001) with non significant relation to tumor type. Also, patients with different histopathologic diagnoses had comparable median MVC (tissue angiogenesis) with non significant intergroup variability. Serum VEGF increased significantly in patients with neuroblastoma (n = 19) compared to those with ganglioneuroma (n = 6) while MVC values were comparable. When patients with metastatic cancer (n = 15) were compared to those with localized disease (n = 30), median VEGF levels and MVC were slightly higher in the former group, the difference did not reach statistical. In all cancer patients (n = 45), VEGF values correlated with MVC (r = 0.33, p = 0.022). After treatment, serum concentrations of VEGF dropped significantly (p<0.001) but still higher than control values (p =<0.001). Estimated OS and EFS of the whole group with malignant solid tumors patients were 86 and 72%, respectively. Serum VEGF did not correlate with outcome for the whole group of patients. Cox regression revealed that MVC (p<0.001) and stage of cancer (p<0.001) were highly associated with EFS of patients with embryonal tumors. Tumor angiogenesis can be indirectly assessed in vivo by serum VEGF measurement which is correlated with tissue MVC. Also, monitoring the levels of VEGF in patients with cancer may prove to be a useful marker for tumor status and response to treatment.