It has been demonstrated that angiogenesis is required in the process of tumor progression and metastasis. Microvessel density (MVD) estimates tumor angiogenesis and is an independent indicator for predicting tumor metastasis in a variety of carcinomas. Platelet-derived endothelial cell growth factor (PD-ECGF) is known to be an angiogenic factor in vitro and in vivo. Of 55 patients with oral squamous cell carcinoma (OSCC), regional metastasis was absent in 35 and present in 20. Cases with lymph node metastasis showed significantly higher MVD (mean 61.0 +/- 28.8) than those without metastasis (mean 29.3 +/- 15.1; p < 0.001). A total of 37 cases (67.3%) were PD-ECGF-positive with a high MVD (mean 47.8 +/- 27.9) and 18 (32.7%) showed a negative PD-ECGF expression with a low MVD (mean 26.6 +/- 13.2). PD-ECGF expression was significantly correlated with the increment of MVD (p < 0.01). We suggest that MVD can be used as an independent prognostic indicator for predicting metastasis and that PD-ECGF activity plays an important role in the neovascularization of OSCC.