Background: Programmed cell death protein 1 (PD-1), an immune checkpoint molecule, has recently been recognized as a predictive and prognostic biomarker in several malignant tumors, but its diagnostic value remains largely unknown. Aim: We aimed to investigate the differential diagnostic efficiency of PD-1 and other immune molecules, and propose a panel of immune molecules combined with cancer antigen 15-3 (CA15-3) to distinguish breast cancer (BC) from benign breast disease (BBD). Methods: Ninety-one eligible BC patients and 31 BBD patients were enrolled. Pretreatment peripheral blood was collected and tested for mRNA expression of PD-1, cytotoxic T lymphocyte antigen 4 (CTLA-4), forkhead box P3 (FOXP3), transforming growth factor beta (TGF-β), interleukin-10 (IL-10), IL-2 receptor alpha (IL-2Rα), and cluster of differentiation 28 (CD28) by quantitative real-time PCR. Results: The diagnostic areas under curve (AUCs) of PD-1, IL-2Rα, and IL-10 for BC-BBD discrimination were 0.764, 0.758, and 0.743, respectively. The diagnostic efficiencies of these 2 parameters in distinguishing early-stage or advanced BC from BBD were consistent with a role in BC-BBD discrimination. A panel of PD-1 + IL-10 + IL-2Rα + CA15-3 showed the highest AUC (0.862), with sensitivity of 0.933 and specificity of 0.724, for BC-BBD discrimination. In addition, for early-stage BC discrimination, this panel also had the highest AUC (0.811), with a sensitivity of 0.933 and specificity of 0.614, while for advanced BC discrimination, a panel of PD-1 + IL-10 + CA15-3 exhibited the highest AUC (0.896), with a sensitivity of 0.933 and specificity of 0.783. Conclusion: These data indicate that the panel containing PD-1, IL-2Rα, IL-10, and CA15-3 can effectively discriminate BC from BBD with a high efficiency. After further confirmation, it could be used to complement conventional imaging modalities, especially in discriminating early-stage BC from BBD.