The objective of this study was to evaluate Aurora-A expression in human renal cell carcinomas (RCCs) to clarify the clinical significance of Aurora-A expression in this disease. Expression levels of Aurora-A messenger ribonucleic acids and proteins in both normal kidney and RCC specimens obtained from 131 patients undergoing radical nephrectomy were determined by real-time reverse transcriptase polymerase chain reaction and immunohistochemical staining, respectively. Various levels of Aurora-A protein expression were noted in 127 of the 131 RCC specimens (96.9%), while only 101 of the 131 normal kidney tissues (77.1%) showed Aurora-A staining. In addition, the expression levels of Aurora-A protein in both normal and RCC specimens were in proportion to those of Aurora-A messenger ribonucleic acids. Aurora-A protein expression in RCC tissues was significantly related to tumor grade, but not with age, gender, tumor size, pathologic stage, or histologic cell type. Cell proliferative activity in RCC specimens was significantly associated with Aurora-A expression, while there was no significant correlation between the apoptotic index and Aurora-A protein expression. Furthermore, there was no significant difference in recurrence-free survival between patients with strong Aurora-A expression and those with weak expression. In conclusion, despite the detection in the majority of RCC tissues, Aurora-A expression failed to show the significant association with major pathologic factors and prognosis in patients with RCC.