Angiogenesis is an essential process for the growth, invasion and metastasis of cancer. However, it is uncertain that antiangiogenic effects can be a major treatment strategy of oral cancer. The aim of this study was to investigate whether thalidomide, which is known to be a potent inhibitor of angiogenesis, have inhibitory effect on the growth and antiangiogenic effects of oral squamous cell carcinoma(OSCC) xenografted in nude mice and whether antiangiogenesis of thalidomide can be included as a major treatment strategy of oral cancer. After human oral squamous cell carcinoma strain KB was subcutaneously implanted in 20 nude mice, the volume of tumor was measured every three days. When the tumor mass reached $75{sim}100mm^3$, thalidomide(200mg/kg/d) was administered into 10 experimental nude mice and the same volume of distilled water was administered into 10 control nude mice and the tumor volume was measured every three days. The excised tumor masses on the 30th day after administration were frozen and processed for immunohistochemistry using vascular endothelial growth factor(VEGF) and CD31. We evaluated microvessel density and VEGF expression. The results were as follows ; 1. Thalidomide retarded the growth of human OSCC as compared with the control group, but it was not statistically significant. 2. A statistically significant lower microvessel density was observed in the thalidomide-treated group than in the control group(p<0.01) and thalidomide significantly reduced VEGF expression (p<0.01). Thalidomide exhibited significantly antiangiogenic effect, but did not inhibit the growth of human OSCC effectively. Antiangiogenic therapy of thalidomide alone is not likely to be effective in the treatment of human OSCC, but might be regarded as adjuvant chemotherapeutic strategy.