Recent advances in endoscopic imaging technology have enabled the visualization of early-stage cancer and its precursors in the gastrointestinal tract. Chromoendoscopy, magnifying endoscopy, endoscopic optical coherent tomography, spectroscopy, and various combinations of these technologies, are all important for the recognition of small and unclear lesions. To observe cancer cells in vivo, two types of ultra-high magnifying endoscope--'laser-scanning confocal endoscopy series' and 'contact endoscopy series'--that have a maximum of more than 1,000x magnifying power have been developed. These endoscopes can generate high-quality images of both living cancer cells and normal cells in the gastrointestinal tract, with a quality comparable to that possible with conventional cytology. These novel imaging technologies may make in vivo histological diagnosis by virtual histology possible.