The angiogenesis process is a pivotal cellular process involved in both developmental and pathological circumstances. In this study we investigated effect of Urtica dioica agglutinin (UDA), as an unusual phyto-lectin from the chitin-binding protein family, on the angiogenesis of chicken embryos. The UDA was extracted from plant rhizomes and purified by affinity chromatography column. The activity of this lectin was assayed by hemagglutination test on the human RBCs. Anti-angiogenic effect of UDA on the extra-embryonic layer of the chick egg was studied in the different concentrations. Our results showed that the minimum concentration of UDA for agglutination were 48.00 and 15.00 µg mL-1 in macro- and microscopic studies, respectively. Because the number and length of the vessels were dramatically decreased at 100 µg kg-1 of UDA, the lectin had an inhibitory effect on angiogenesis of the embryonic vasculature of the chick. We concluded that UDA might target the vascularization events through binding to GlcNAc-conjugates. More investigations are needed to clarify the angiogenesis-related therapeutic roles of this interesting biomolecule.