Abstract: A hand-held, small, lightweight instrument is disclosed that contains a light source capable of producing radiant energy in the spectral range between approximately 370 and approximately 410 nm, and an optical direction system for irradiating a target tissue by producing an illuminated spot thereon. A collection system is provided for receiving and directing fluorescent emissions in the frequency range between 450 and 700 nm returned from the target area to a detector. A processing system is used to determine the state of the tissue by using at least two and up to five spectral bands, preferably each being larger than 45 nm. Pairs of ratios of fluorescent intensities are compared to identify cancerous cells. An alphanumeric, false-color image and/or audio signal is immediately provided to inform a user of the state of the tissue.