Vascular Endothelial Growth Factor Receptor 3 (VEGFR-3) is a very important factor which promotes lymphangiogenesis not only in physiological but also in pathological processes in which we can include neoplasia. The aim of this study was to analyze the plasma concentrations and diagnostic utility of this parameter in comparison and in combination with CA 15-3 in breast cancer (BC) patients and in relation to the control groups. The study included 120 breast cancer and 60 control patients (28 with benign breast tumors and 32 healthy women). Plasma levels of VEGFR-3 were determined by an Enzyme-Linked Immunosorbent Assay (ELISA), and those of CA 15-3 by a Chemiluminescent Microparticle Immuno Assay (CMIA). Differences in concentrations of both of the tested parameters were statistically significant when breast cancer patients were compared to the control groups. VEGFR-3 had higher values of sensitivity (SE), specificity (SP), predictive value of a positive (PPV) and negative test result (NPV) in the whole BC group (90%; 98.33%; 99.08%; 83.10%, respectively) and, more importantly, in the early stages of BC, than CA 15-3. VEGFR-3 was also a better parameter in terms of statistically significant Area Under Curve (0.9656) in the whole group and at all BC stages (I-IV), but a maximum range was obtained for the combination of VEGFR-3 and CA 15-3 (0.9710). The combined analysis of VEGFR-3 and CA 15-3 provides hope that a new BC diagnostic panel may be developed in the future.