Parathyroid hormone-related peptide (PTHrP) participates in the development of humoral hypercalcaemia of malignancy. The peptide is thought to affect growth and differentiation of normal and neoplastic cells. The present study aimed at evaluation of the relationship between survival time and development of distant metastases in patients with ductal mammary carcinoma on the one hand and PTHrP expression on the other. Immunocytochemical reactions using mouse monoclonal (clone 212-10.7) anti-PTHrP (38-64) antibodies were performed in paraffin sections originating from 47 patients with ductal mammary carcinoma. Expression of the protein was quantified employing a scale, considering the number of positive cells and intensity of the reaction (immunoreactive score, IRS). Survival time of the patients, determined during the course of a 7-year observation was also analysed. The obtained results demonstrated a relationship between intensity of PTHrP expression and the survival time. Patients with high expression of PTHrP (IRS>6) manifested longer survival than patients with lower PTHrP expression (IRS< or =6; Cox'es F test, P<0.05). Moreover, in the group with the lower PTHrP expression, a negative relationship was detected between expression of the protein and the survival time (Cox'es model, P<0.05). No relationship was detected between PTHrP expression and the development of distant metastases.