BACKGROUND Vascular endothelial growth factor (VEGF) is a critical promoter of blood vessel growth during embryonic development and neovascularisation in tumours. VEGF serves as a logical target for antiangiogenic cancer therapy because of its fundamental role in tumour angiogenesis. This study is to investigate the inhibitory effects of FP3, a novel VEGF blocker, on angiogenesis in vitro and tumour growth in vivo. METHODS The inhibitory effects of FP3 on angiogenesis in vitro were evaluated by using human umbilical vein endothelial cells (HUVECs) and rat aortic ring. The inhibitory effects of FP3 on tumour growth and angiogenesis in vivo were evaluated in a human non-small-cell lung cancer (NSCLC) cell line A549 tumour xenograft model with the methods of tumour growth regression assay and immunohistochemical staining, respectively. RESULTS In experiments with HUVECs, FP3 inhibited cell proliferation and migration. In rat aortic ring assay, FP3 suppressed VEGF-induced vessel sprouting. In tumour growth regression assay, FP3 significantly blocked the growth of A549 tumour in the subcutaneous tumour xenograft model and dramatically decreased the vessel density of tumour. CONCLUSIONS FP3 has excellent inhibitory effects on tumour angiogenesis both in vitro and in vivo, therefore it could be used as an effective antiangiogenic agent.