- Fourier-transform infrared spectroscopy (FT-IR) employs a unique approach to optical diagnosis of tissue pathology based on the characteristic molecular vibrational spectra of the tissue. In this study, we report infrared absorption spectra of for- malin fixed, paraffin embedded normal and malignant human colonic tissues from ten different patients. Our method is based on microscopic infrared study (FT-IR-microscopy) of thin tissue specimens in parallel with normal histopathological analysis, which serves as a reference. Our results indicate that the normal colonic tissue has a stronger absorption than the cancerous type over a wide region in all ten cases. The detailed analysis showed that there is a significant decrease in carbohydrate levels, total phosphate and also possibly creatine contents for cancerous tissue in comparison to the controls. Also, RNA/DNA ratio increased in cance- rous tissues relative to the normals in all the patients. The results of Linear Discriminant Analysis (LDA) showed that the normal and malignant cells could be identified with about 89% accuracy.