The complete amino acid sequence of a mannose-binding lectin purified from the leaf skin of "Kidachi Aloe" (Aloe arborescens Miller var. natalensis Berger) is presented. The 109-residue sequence of the subunit was determined by analysis of peptides of the intact or S-pyridylethylated protein generated by digestion with cyanogen bromide, BNPS-skatole, Achromobacter protease I, or trypsin. The subunit contains an intrachain disulfide bridge. The sequence is highly homologous to that of a mannose-binding lectin from snowdrop bulb.