Several research groups have been developing optical-spectroscopy methods, often mediated by fibre-optic probes, to noninvasively identify dysplasia and cancer in situ and in real time: often called 'optical biopsy'. Researchers at Los Alamos National Laboratory (Los Alamos, New Mexico) have developed the method of elastic-scattering spectroscopy (ESS). ESS is a point measurement that is sensitive to the morphological changes at the cellular and sub-cellular level, including changes in the size and/or density of the nuclei, mitochondria or other organelles. It is therefore sensitive to morphology features that a pathologist looks for during histological examination. We report on the first stages of a clinical study currently under way at the Middlesex Hospital an University College London, designed to test the ESS method for identification of dysplasia in Barrett's oesophagus. Preliminary results using elastic-scattering spectroscopy during endoscopic examination show that this technique has potential as a real-time test for in vivo detection of dysplasia or early cancer within Barrett's mucosa, or at least as a guide to assist in locating optimum sites for biopsy. Initial data sets are encouraging and the randomly chosen testing and training sets give specificities and sensitivities comparable to the accuracy of histology. It is evident that the ESS technique is proving to be convenient for the physicians given its speed and compatibility with endoscopic equipment. It is intended to begin prospective trials in the next few months to assess the systems suitability for general clinical practice.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.