The aim of this study was to investigate the expression of basic fibroblast growth factor (b FGF) and its relationship with tumor microvasogenesis and biological behavior of human renal carcinoma. Gene expression of b FGF was assayed in 20 cases of renal carcinoma tissue using RNA dot blot hybridization. Meanwhile, the protein expression of b FGF and microvasular density (MVD) was assayed in 35 cases of renal carcinoma tissue with immunohistochemical assay. It was found that the expression of b FGF was significantly higher in renal cancer tissue than in normal renal tissue or normal tissue adjacent to the tumor, There was significant correlation between b FGF expression in cancer tissue and clinical stages as well as clinical grades.Similar results were also observed between MVD and b FGF expression in renal cancer tissue. It seemed that b FGF played an important role in angiogenesis in renal carcinoma. Taken together, the results suggest that MVD and the expression of b FGF in renal cancer tissue might be related to the prognosis of renal carcinoma patients.