Liquid-crystal displays (LCDs) are used for displaying medical images under various illuminance conditions and with ambient-lighting colors. Our purpose in this study was to understand the variations of the chromaticity in LCDs under different fluorescent lighting conditions. The variation of chromaticity of LCDs at a white point consisting of equivalent pixel value in Red, Green, and Blue was examined under different types of fluorescent lighting. The direction of changes in the chromaticity diagram shifted to the color of each fluorescent lighting. When the differences in chromaticity (∆u'v') increased, the observers' confidence levels in distinguishing color differences also increased. When the luminance of the LCD increased, observers' sensitivities for recognizing differences in chromaticity also increased as compared to observers' sensitivities at lower luminances. Our results indicate that observers recognized slightly yellowish colors even if ∆u'v' was less than 0.01; thus, observers could perceive differences in chromaticity. These results could provide important and relevant information with regard to better ambient lighting conditions in an image-reading room.