Background: Edema represents a key feature of nasal polyp (NP) disease. Members of the vascular endothelial growth factor (VEGF) family may be involved, but the precise role of VEGF-A, VEGF-B, placental growth factor (PlGF), and their receptors VEGFR1 and VEGFR2 in NP edema formation remains elusive. Objective: Exploring the expression of VEGF family members and their receptors and their correlation with clinical, radiological, and edema markers in NP. Methods: The expression of VEGF-A, VEGF-B, PlGF, VEGFR1, and VEGFR2 was measured in NP (n=23) and control tissue (n=22) at mRNA and protein level. Edema was evaluated by measuring albumin levels and wet/dry ratios. Computed tomography (CT) scans were scored using the Lund-Mackay scoring system. IL-5 mRNA expression was determined by real-time RT-PCR. Cell suspensions from NP (n=10) and control tissue (n=12) were stimulated in vitro with IL-1 or TNF. Results: mRNA expression of VEGFR1 and VEGF-B was significantly higher in NP compared with control tissue. Expression levels of VEGF-B and VEGFR1 significantly correlated with NP albumin content (VEGF-B: P=0.0208; VEGFR1: P=0.0293), CT scan scores (VEGF-B: P=0.0075; VEGFR1: P=0.0068), and IL-5 mRNA (VEGF-B: P=0.0027; VEGFR1: P=0.0001). In vitro stimulation of control and NP tissue cell suspensions with IL-1 or TNF significantly reduced the expression of VEGFR2 in control tissue, without altering VEGFR1 and VEGF-B expression. hVEGF-B induced nitric oxide production in NP macrophages (P