A color notation conversion program was used to compare the perceptual scaling of the Munsell, NCS, DIN, and Coloroid systems with that of the OSA-UCS system. Five OSA-UCS cleavage planes were selected. These planes represented a varied but systematic sampling of the OSA-UCS color space. The samples contained in these planes were converted onto the color spaces of the Munsell, NCS, DIN, and Coloroid systems. The converted points were displayed graphically to ease comparisons. It was clear that the Munsell system most closely approximated the OSA-UCS color space. The NCS showed radical differences in the hue scaling, while the DIN and the Coloroid saturation scales were radically different from the OSA-UCS chroma scale and from each other.