The EtOH extract of gardenia (Gardenia jasminoides Ellis) fruits was previously found to possess potent anti-angiogenic activity in the chick embryo chorioallantoic membrane (CAM) assay. Bioassay-guided fractionation and purification of the EtOH extract yielded an active anti-angiogenic compound, which was determined to be an iridoid glucoside, geniposide, by spectral analyses. Geniposide showed anti-angiogenic activity in a dose-dependent manner. It also exhibited an inhibitory effect in the range of 25 - 100 μM on the growth of the transformed NIH3T3 cell line.