A retrospective study of 167 consecutive radically treated breast cancer patients with histopathologically confirmed ductal carcinoma is presented. The aim was to establish the prognostic significance and reproducibility of histopathological grading done independently by two pathologists. Further-more, the value of measurements of mean nuclear area (MNA) in the primary tumour was assessed. The two pathologists reviewed the same histological sections using a three-point scoring system based on tubular structures, number of mitoses and nuclear pleomorphism. Grading was identical for 70% of the tumours (Kappa value 0.51). With increasing MNA, the fraction of poorly differentiated tumours increased. In the univariate analysis, tumour-related survival was significantly related to histopathological grading when G3 tumours were compared to G1/G2 tumours (p < 0.05). In the multivariate analysis, tumour size (pT category), lymph-node status and grading were the only significant factors influencing patient outcome (p < 0.05). MNA had no significant prognostic value. A combination of tumour size and histopathological grading identifies a group of node-negative patients (pT2 G2/G3) who may have a less favourable prognosis and for whom adjuvant treatment may be beneficial.