High-resolution 1H NMR spectra were obtained from perchloric acid extracts of breast tumor specimens and adjacent non-involved tissue. Two-dimensional shift-correlated and homonuclear J-resolved spectroscopy were used to identify coupled resonances in the spectra. Chemical shifts, multiplicities and spin-spin coupling constants of several non-resolved resonances in the one-dimensional spectra could be determined by the two-dimensional methods. Several differences in the metabolite content of the two types of extracts were established. The spectra of extracts from non-involved tissue were dominated by signals from glucose and other carbohydrates, while most of the tumors had very low or no detectable levels of glucose. High concentrations of lactate, taurine and succinate, an increase of the phosphocholine level, and a very low phosphocreatine level were characteristic findings in the 1H spectra of tumor extracts. The variation in the level of myo-inositol follows the variation in glucose for the two types of tissue. Scyllo-inositol was for the first time observed in the NMR spectra from breast tissue. Uridine 5'-diphospho-N-acetylglucosamine and uridine 5'-diphospho-N-acetylgalactosamine have been identified and there is an increased level of these two hexoses in the tumor tissue. These results provide insight into breast tumor metabolism, by simultaneously detecting a large number of metabolites and demonstrate the potential for using 1H NMR spectroscopy for studying different metabolic pathways in breast tumors. At the same time they provide useful information for interpretation of in vivo 1H NMR spectra of breast tumors.