Molecular biological tumor markers and prognostic parameters are necessary for differential diagnosis, individual prognosis, and therapy in patients with renal cell tumors. By using high throughput technologies for DNA, RNA, and protein analysis, it is possible to comprehensively characterize tumor samples. We identified specific molecular patterns of metastatic tumors, allowing the determination of metastatic potential of the primary tumor. Different therapeutic options are now available for patients with metastatic renal cell carcinoma. Therefore, it is necessary to select the best therapy for each patient and to detect therapy resistance very early. Biomarkers in tumor tissue and serum were found correlating with therapy response.