uPA system plays an important role in cancer invasion and metastasis. The binding of uPA to its receptor, uPAR, is necessary for the activation of uPA system. We studied by immunohistochemistry the distribution pattern of uPAR on 173 paraffin-embedded samples of invasive breast carcinomas in relation to clinicopathologic data and patients' survival. uPAR was detected in both the malignant and stromal cells in the 68.8 and 74.6% of the cases, respectively. uPAR of cancerous cells was more often observed in lobular carcinomas (P=0.012). Stromal expression of uPAR was inversely associated with ER of the tumor (P=0.044) and was found to be an independent prognosticator of patients' shortened relapse-free survival (P=0.018). These results suggest that stromal uPAR influences more directly tumor behaviour, being related to an aggressive tumor phenotype and patients' poor relapse-free survival.