Forty benign and 31 malignant breast tissues were examined using a one stage colloid-stabilising silver technique for argyrophilic nucleolar organiser regions (AgNOR). In 31 patients TNM staging was correlated to AgNOR score. There was a positive correlation with the T-stage and AgNOR score of the tumor (Spearman's rank correlation coefficient = 0.437). The N-stage and AgNOR score for breast cancers (n = 10) were inversely related, and there was a significant difference between the lymph node positive and negative groups (P less than 0.05). No significant relationship was identified between oestrogen receptor negative and positive groups and AgNOR score (P = 0.63). Mean regression analysis suggests that independent of the Bloom's grade, the AgNOR score is an indicator of tumour size.