To evaluate the malignant potential of a tumor, data about its proliferative rate are essential. In this study clinical data, histological grading and immunohistochemical marker PCNA were applied on astrocytomas in childhood and were correlated to number, size and distribution of AgNORs. Tumor material from 90 patients, aged 1 to 15 years, was available. Histological grading, immunohistochemistry and AgNOR staining were performed on paraffin sections. PCNA-positivity was evaluated semiquantitatively. The AgNORs were quantified on 100 nuclei/case with an image analysis system. With aggravating malignancy we could show a shorter anamnesis, a lower survival and a higher PCNA-reactivity. We found a strong correlation between several AgNOR-features and the grade of malignancy of the astrocytomas, especially for the number of the AgNORs (from grade I: 1.73 AgNORs/nucleus to grade IV: 4.56 AgNORs/nucleus), the size of the AgNORs and its area amount of the nucleus. There were correlations between AgNOR-number and PCNA-reactivity as well as AgNOR-number and survival. Analysis of AgNORs, consequently, should provide prognostically relevant information helpful in more effective grading of astrocytomas.