Malignant tumors have a capacity to degrade the extracellular matrix by controlled proteolysis. One system involved in these processes is the urokinase-type plasminogen activator (uPA) system. uPAR levels are elevated in tumors from several types of cancer. Our study was planned to investigate serum and urine levels of uPAR in breast cancer patients (n=180) and healthy controls (n=60) by ELISA. Serum (p<0.001) and urine (p<0.001) uPAR values in the patients were both significantly elevated. High serum and urine levels of uPAR can be used as diagnostic tools in lymph node positive patients.