Accurate relationships between color and other soil characteristics  require increasing precision  in color measurements, illumination playing a very important role in such a measurements. Color-assessment cabinets provide a standard although non-uniform illumination, and they are often used to achieve precise  color measurements of soil samples in the laboratory . We report an experimental study on the uniformity of lighting  of a commercial color-assesment cabinet, with daylight (D65) and incandescent (F) light sources, and the color differences found in such a cabinet for 12 soil samples, from Entisols, Inceptisols, Mollisols and Alfisols. The D65 source showed better temporal stability than did the F source. Maximum displacements of the soil samples inside the color-assessment cabinet (26.0) led to average color differences of 1.8 and 2.4 CIELAB units, for D65 and F, respectively. Lightness differences were the main component of such a color differences. Color differences of object colors illuminated with daylight at the maximum solar elevation and at twilight normally exceed 3.0 CIELAB units ( Color Res Appl 28, 25-35, 2003) Average color differences of soil samples, assessed with standard soil-color charts by experienced observers in a color-assessment cabinet, are 5.0 and 12.7 CIELAB units, for disturbed and undisturbed samples, respectively (Recent Res. Devel. in Soil Science, 1, 17-27, 1997) It can be concluded that color differences for a soil sample placed at different  positions inside a color- assessment  cabinet would be negligible in most practical situations, bearing in mind that displacements of the sample should be about one half the maximum ones, this leading to color differences below 1.0 CIELAB units.