Background: Angiogenesis is a key process in the development of a malignant tumor, enabling both growth of primary lesion and spread of metastases. Most potent stimulators of normal and pathological angiogenesis are proteins of the vascular endothelial growth factor (VEGF) family. Regulation of angiogenesis process is also mediated by neuropilin-1 (NP-1), as coreceptor VEGFR-2. NP-1 plays a crucial role controlling both normal angiogenesis during embryonal development and pathological angiogenesis in malignant tumors. The aim of this paper was to assess NP-1 expression in ovarian cancer and to analyze correlations between NP-1 expression and selected clinical-pathological factors in a group of ovarian cancer patients. Material and method: Analyzed was the relative level of NP-1 in 168 surgical specimens collected during surgical procedures performed at the Department of Oncologic Gynecology of Medical University in Gdańsk. Tissue samples included: 32 healthy tissues, 42 benign tumors, 10 borderline tumors, 76 ovarian cancers, 8 metastatic tumors. Relative NP-1 level was assessed using Western blotting technology. Results: Overexpression of NP-1 was seen significantly more often in early clinical stages of ovarian cancer (p=0.01), in cancers other than serous (p=0.04) and in patients with peritoneal exudate (p=0.03). Log-rank test did not reveal any significant correlation between NP-1 expression and favorable response to chemotherapy, disease-free survival or total survival time. Conclusions: Elevated NP-1 level seen in initial clinical stages of ovarian cancer may indicate crucial role of neoangiogenesis in the early phase of tumor development.