Excessive or insufficient angiogenesis is associated with major classes of chronic disease. Although less studied, small molecules which can promote angiogenesis are being sought as potential therapeutics for cardiovascular and peripheral arterial disease and stroke. Here we describe a bioassay-directed discovery approach utilising size exclusion and liquid chromatography to purify components of soybean xylem sap that have pro-angiogenic activity. Using high resolution accurate mass spectrometry and nuclear magnetic resonance spectroscopy, the structure of two pro-angiogenic molecules (FK1 and FK2) were identified as erythro-guaiacylglycerol-8-O-4'-(coniferyl alcohol) ether (eGGCE), and threo-guaiacylglycerol-8-O-4'-(coniferyl alcohol) ether (tGGCE). These two molecules, which are coniferyl neolignan stereoisomers, promoted in vitro angiogenesis in the μM to nM range. Independently sourced samples of eGGCE and tGGCE exhibited comparable pro-angiogenic activity to the soybean derived molecules. The cellular mode of action of these molecules was investigated by studying their effect on endothelial cell proliferation, migration, tube formation and adhesion to the extracellular matrix (ECM) components, fibronectin and vitronectin. They were found to enhance endothelial cell proliferation and endothelial cell tube formation on Matrigel, but did not affect endothelial cell migration or adhesion to fibronectin and vitronectin. Thus, this study has identified two coniferyl neolignan stereoisomers, eGGCE and tGGCE, as pro-angiogenic molecules, with eGGCE being less active than tGGCE.