Silver colloid staining of nucleolar organiser regions (AgNORs) is used for assessing the proliferative potential of tumours. The present study aimed at evaluating the AgNOR indices in normal and reactive CNS tissue, benign and malignant CNS neoplasms. The study group comprised of tissue from 22 controls and 100 cases (53 benign & 47 malignant neoplasms). The mean AgNOR index of controls was 0.95, benign neoplasms 1.25 and malignant neoplasms 2.12. A statistically significant difference was observed in controls and cases (p < 0.001) and between benign and malignant tumours (p = 0.002). Mean indices for low and high grade astrocytoma also significantly differed (p < 0.001). Using ROC curves cut off values were obtained for differentiation of neoplastic from non neoplastic (AgNOR index 1.10), benign from malignant (AgNOR index 1.75) and low grade (I & II) from anaplastic (Gr III & IV) Astrocytomas (AgNOR index 1.62). A spectrum of gradually increasing AgNOR indices from normal, reactive, benign to low and high grade malignancy indicates the usefulness of this simple technique as a proliferative marker.