The authors detected ten normal breast tissue samples and eight breast cancer samples by FTIR spectroscopy with an ATR probe. Nineteen variables of thirteen bands in the spectra were compared using standard statistic methods. The results demonstrated that bands of protein, lipid, carbohydrate, and nucleic acid from cancerous samples were significantly different from those from normal ones: (1) The relative intensity of N-H band increased and amide I band shifted to lower wave number significantly; (2) Symmetric and antisymmetric vibrations of -CH2 group, C=O vibration, and relative intensity of (-CH2)n decreased; (3) The intensity of 1160 cm(-1) band was much weaker than that of 1120 cm(-1); (4) The band of P=O or P-O-C shifted toward lower wave number. The authors believe that FTIR spectroscopy has a promising future in breast cancer diagnosis.