Tumor markers are mainly used to diagnose specific malignancies. The methods commonly involve immunohistochemistry and cytogenetics, including FISH and RT-PCR. In RCC, the investigated tumor markers (summarized in Table 1) show additional prognostic value over classical prognostic factors such as stage and grade. These markers can be used for better patient selection, a more accurate individualization of treatment, and improved follow-up. Nevertheless, their definitive value must be reconfirmed in larger patient cohorts. Ultimately, these factors should be shown to be of value in a prospective well-controlled trial. One of the most promising new techniques involves gene expression profiling of solid tumors. This cDNA microarray technique applied in RCC has improved understanding of the molecular mechanism of the underlying tumor genesis and its correlation to the clinical course. Tumor antigens that are specific for RCC (eg, G250) and that induce a specific immune response can be used for vaccine treatment modalities. With the use of dendritic cells, antigen presentation can be improved. Several phase I studies are currently underway. More research is needed to obtain better antigens and markers in RCC to improve insight into the molecular mechanism of the development of RCC, to improve the selection of patients for treatment, and to increase its effectiveness.