Image quality of the electronic endoscopes are poor compared to the conventional optical endoscopes which use color film. It is our goal to improve the image quality, particularly color reproduction of electronic endoscopes.To achieve our goal, we have developed the endoscopic spectrophotometer to measure the spectral reflectance of gastric mucous membrane. The instrument consists of a light source with xenon lamp; a conventional spectrophotometer; an optical multichannel analyzer with 1024 silicon photodiodes; and personal computer. Three hundred and ten spectra have been analyzed by the principal component analysis. The results indicate that the reflectance spectra can be adequately described less than the average color difference ΔE = 2.66 in the L*u*v* color space using only three principal components.Based on the above experimental result, it is shown that the spectral reflectance of all pixels in gastric mucous membrane can be calculated from the R, G, B signals of the conventional electronic endoscopes. Computer simulations of the color reproduction of electronic endoscopes were performed, and the resulting spectral characteristics under different illuminants are described and analyzed.