In this work the infrared absorption spectra of intercellular fluid of normal and tumor kidney tissue were recorded and analyzed. The samples were prepared by stamping freshly resected tissue onto a CaF₂ substrate. FT-IR spectra obtained from intracellular fluid of tumor tissue exhibit stronger absorption bands in the spectral region from 1000-1200 cm^-1 and around 1750 cm^-1 than those obtained from normal tissue. It is likely the spectra of extracellular matrix of kidney tumor tissue with large increases in the intensities of these bands represent a higher concentration of fatty acids and glycerol. Amide I and amide II bands are stronger in spectra of normal tissue indicating a higher level of proteins. The results demonstrate that FT-IR spectroscopy of intercellular fluids is a novel approach for a quick diagnosis during surgical resection, which can improve the therapy of kidney tumors.