Heparan sulfate (HS), which is degraded by heparanase, plays an important role in cell adhesion, insolubility of the extracellular matrix (ECM) and as a reservoir for various growth factors such as basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF). In the present study, we examined the immunohistochemical expression of heparanase, bFGF and VEGF, and evaluated the correlation between their expression and microvessel density (MVD) in human esophageal carcinomas. Heparanase, bFGF and VEGF were immunolocalized predominantly to the carcinoma cells, but they were also localized to the endothelial cells of microvessels near the carcinoma cell nests. In carcinomas with invasion of the muscular layer or adventitia, heparanase staining was stronger at the invasive areas of carcinomas than the intraepithelial spread. Expression of heparanase and bFGF and the degree of MVD were associated with tumor invasion, lymph node metastasis and pathological stages. Cases with positive staining for heparanase, bFGF or VEGF tended to have a higher MVD than those without staining, and carcinomas with concomitant expression of heparanase, bFGF and VEGF showed the highest MVD. The level of heparanase mRNA expression was directly correlated with the MVD. In addition, heparanase-positive cases had a higher positive ratio of bFGF and VEGF compared with the heparanase-negative cases. These data suggest the possibility that heparanase may contribute to not only cancer cell invasion but also angiogenesis probably through degradation of HS in the ECM and release of bFGF and VEGF from the HS-containing ECM.