Normal liver biopsies of 14 volunteers were investigated ultrastructural morphometrically. Besides the determination of morphometric baseline data for comparative purposes particular emphasis was placed on the question, if morphometric evaluations of human livers yield reliable results in spite of the higher range of distribution than in experimental liver material. The results showed that the surface of the smooth endoplasmic reticulum of human liver is significantly greater than the surface of rough endoplasmic reticulum. Otherwise the morphometric data of the human liver tissue did not differ essentially to the values of the laboratory rat. The variance analytical consideration of the mean evaluated from the data of the 14 liver biopsies indicated that the standard error of nearly all proved parameters was less than 10% of the mean. The results suggest that ultrastructural morphometric evaluation of human liver biopsy samples yield reliable results provided the samples investigated are sufficiently extensive.