The silver-staining technique for nucleolar organizer regions (AgNOR) of Ploton et al, as popularized by Crocker et al, is being widely used for evaluation of nucleolar function, especially in neoplasia. This work is carried out to evaluate the usefulness of AgNOR technique in the differentiation between benign and malignant lesions in urine cytology, and to evauate the correlation of AgNOR count and morphology with tumor grade and patients' sex. Urine samples from sixty-four patients were centrifuged, deposits smeared on slides and stained with Hematoxylin and Eosin (H&E) and AgNOR stain. The diagnosis of each patient had been established depending on histological analysis of bladder biopsies and the diseases were classified into three groups: non-neoplastic lesions (n=34), low grade carcinoma (n=12) and high grade carcinoma (n=18). AgNOR counts, variation in size and distribution of AgNOR dots in smears were graded and compared in the three groups. The correlation between AgNORs and patients' sex was also analyzed.