Background and Aim: To correlate stereological parameters to the WHO morphological classification of brain tumours and to address the prognostic value of the different parameters. Methods and Materials: A quantitative analysis of 50 astrocytomas was performed by an image analysis system. At least 450 nuclei were counted and measured in every sample. The ANOVA 1-way test and Newman-Keuls modification were used for statistical evaluation. Results: The morphometric data showed significant differences between the tumour grades. We found the nuclear volume and form factor to be parameters of the degree of ‘nuclear atypia’ from low- to high-grade gliomas. When malignancy was increased, the mean values of nuclear orientation were found to be elevated. Conclusions: The results of our study underline the usefulness of morphometric techniques in tumour research. These techniques seem to be an important tool for grading gliomas and also for practical therapeutic purposes.