The authors illustrate the need for the best possible level of objectivity and reproducibility in diagnostic pathology. Morphometry may help considerably in this attempt, in particular in basing the classification of neoplasms on a quantitative basis and in differentiating one type of neoplastic growth from another. Since anisotropic tissue or cell components are not suitable for stereological analysis and thus limit the applicability of stereological methods to pathology, planimetric morphometry remains the most important quantitative technique to be applied to tissue sections, smears and imprints. The counting process, analysis and reporting of results are helped by computer based graphic tablets; with these systems, parameters, such as profile, perimeter and various form factors, can be obtained. Flow cytometry is a widely efficient method for obtaining ploidy patterns of a given cell population, with a more acceptable reproducibility than that of static cytometry. Methods for quantifying the chromatin distribution in cell nuclei, such as digital image analysis and, even more so, laserscan microscopy, are of the greatest importance in oncological pathology. It will be essential in the near future to combine results of quantitative structural analysis with findings made with the help of immunocytochemical, cytogenetic and "in situ" hybridization techniques.