Renal cell carcinoma (RCC) has been shown to respond to an immunological therapy with tumor infiltrating lymphocytes (TIL), which accumulate in RCC at a higher density than in normal renal tissue, suggesting that there is selective tumor invasion. Since invasion of TIL into the malignant tissue is mediated by adhesion molecules, we examined the different expression of the adhesion molecule endothelial-leukocyte-adhesion-molecule-1 (ELAM-1) on endothelial cells of RCC versus normal renal tissue. For a specific quantification, the level of ELAM-1 mRNA was investigated by both semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis and referred to the content of endothelial cells in the tissue, determined by endothelium specific staining. Quantification of mRNA was evaluated by computer-aided integration. We observed a significantly lower amount of endothelial cells in RCC compared to normal renal tissue. The specific transcription rate of ELAM-1 in RCC, determined by RT-PCR was about 5.2 times that of normal tissue, while Northern blot analysis indicated an approximately 11.8 times increase. Our investigations show a significantly increased expression of ELAM-1 in tumor tissue compared to normal renal tissue, presumably caused by a higher amount of cytokines in the tumor tissue. This enhanced expression may be responsible for the high concentration of TIL in renal tumors.