New data have been reported on Fourier-transform infrared spectra in 97 samples of resected material taken from normal and malignant tissues of the human stomach. Malignant tissues revealed a significant drop in peak intensity of vsPO2 bands (approximately 1089 cm-1) of nucleic acids characterized by the prevalence of high-frequency vCH3/ vCH2 protein and lipid fragments, the narrowing of vC=O bands of phospholipids, the simultaneous growth and narrowing of amide-I and amide-II bands, an increased homogeneity of the spectra, etc. Statistical data on the differences in normal and malignant tissue samples and diagnostically relevant criteria are presented.