The real finite section thickness of histologic slices is one of the dominant artefacts in morphometrical studies. Investigations without correction of the section thickness error are not reproducible or comparable. On this basis we measured the real finite section thickness of histologic slices with a nominal section thickness of 2, 4 and 6 microns with a microinterferometrical method. We also estimated the size of the error of a fictive volume density and a fictive Sholpo-correction. On the nominal section thickness of 2 and 6 microns we determined significant differences between the nominal section thickness and the real finite section thickness. We found analogue differences in the estimation of the fictive volume densities and in the fictive Sholpo-corrections. We did not determine a significant difference between the real finite and the nominal section thickness for the nominal section of 4 microns. We also could not determine significant differences between the real and nominal fictive volume densities and Sholpo-corrections. The measurement errors are discussed, and a test of reproducibility was performed.