Blood supply plays a crucial role in solid tumour development and leukaemogenesis. It has been suggested that blocking of angiogenesis could be possible in cancer therapy. We have demonstrated the antiproliferative activity of Gleditsia sinensis fruit extract (GSE) on various human solid tumour cancer cell lines as well as leukaemia cell lines and primary cultured leukaemia cells obtained from leukaemia patients. However, the antiangiogenic potential of GSE has not been demonstrated. Here we demonstrated that GSE could reduce vascular endothelial growth factor (VEGF) mRNA expression in dose- and time course-dependently in MDA-MB231 breast cancer and HepG2 hepatoblastoma cell lines as measured by reverse transcriptase polymerase chain reaction. Enzyme-linked immunosorbent assay further showed that GSE could reduce the VEGF secretion from various cancer cell lines including MDA-MB231, HepG2, HL-60 (acute promyelocytic leukaemia) and eleven primary cultured leukaemia cells obtained from acute myelogenous leukaemia patients. In vivo chick chorioallantoic membrane assay illustrated that GSE could reduce the angiogenic activity of basic fibroblast growth factor. Taken together, the information suggested that GSE could be potentially used as an angiogenic inhibitor in both solid tumour and leukaemia therapy.