The concentration of total cathepsin D in cytosols of 199 node negative women with primary breast cancer in a 10-year retrospective cohort was assayed. Cathepsin D status alone was unable to predict disease-free or overall survival. However, those patients with receptor positive tumours who were cathepsin D positive had shorter [corrected] disease-free (P = 0.02) and overall survival (P = 0.01) than cathepsin D negative patients. Therefore, measurement of cathepsin D appears to provide additional prognostic information for the prediction of disease-free and overall survival in patients with node negative breast cancer.