Abstract: Systems and methods are described for improved diagnostic fluorescence and reflectance. A method of detecting tissue abnormality in a tissue sample in vivo detects a set of reflectance spectra emitted from a tissue sample as a result of illumination with an excitation light from a fiber optic probe that has at least one collection fiber positioned at a source-detector separation, and determining if the tissue sample is normal or abnormal based on the resulting reflectance spectra. Another method of detecting tissue abnormality in a tissue sample in vivo includes illuminating the tissue sample in vivo with at least one electromagnetic radiation wavelength selected to cause the tissue sample to produce a set of fluorescence intensity spectra indicative of tissue abnormality, detecting the resulting fluorescence intensity spectra, and determining if the tissue sample is normal or abnormal based on the resulting fluorescence intensity spectra.