BACKGROUND: Previous studies had explored the diagnostic or prognostic value of NRP-1/CD304 in blastic plasmacytoid dendritic cell neoplasm (BPDCN), acute myeloid leukemia (AML) and B-cell acute lymphoblastic leukemia (B-ALL), whereas the expression and application value of NRP-1/CD304 in other common hematological diseases have not been reported. METHODS: Bone marrow samples from 297 newly diagnosed patients with various hematological diseases were collected to detect the expression of NRP-1/CD304 by ow cytometry (FCM). The diagnostic e cacy of NRP-1/ CD304-positive diseases was analyzed by receiver operating characteristic (ROC) curve, and the area under the ROC curve (AUC) was compared.RESULTS: In the research cohort, the total positive rate of NRP-1/CD304 was 14.81% (44/297), mainly distributed in BPDCN (100%, 6/6), B-ALL (48.61%, 35/72) and AML (4.48%, 3/67), with statistically signi cant differences (P<0.01). Other diseases, such as T-cell acute lymphoblastic leukemia (T-ALL), Bcell non-Hodgkin lymphoma (B-NHL), T/NK-cell lymphoma and plasma cell neoplasms, did not express NRP-1/CD304. The sensitivities of NRP-1/CD304 for BPDCN, B-ALL and AML were 100.00%, 48.61% and 4.48%, as well as the speci cities of which were 87.12%, 96.01% and 82.48%, respectively. The AUC of NRP-1/CD304 was 0.936 (95%CI 0.898 ~ 0.973), 0.723 (95%CI 0.646 ~ 0.801) and 0.435 (95%CI 0.435