It is well known that Phaseolus species contains lectins of various specificities 1-4. Runner bean5 and different varieties of Ph.coccineus described by Ochoa et al6, are not specific to human blood groups. They react indistinctly with erythrocytes of the ABO system. However the lectin of Ph. lunatus (lima bean)7 is specific to the blood group type A, a classic example of that specificity. Sometime ago, we discovered a new lectin in a variety of edible bean of Ph. coccineus in the flora of the state of Oaxaca in Mexico, cultivated exclusively in the small community of Jamiltepec, near the Pacific coast, which presented strong hemagglutinating anti-A1 activity. In this report we describe a chromatographic technique for the isolation and purification of this lectin. The molecule is a tetramer with a molecular weight of 120 kDa. It requires Ca++ or Mg++ for activity, and it is inhibited by N-Acetylgalactosamine (GalNac) at concentration of 2.8 mM., NN' N' Triacetylchitotriose, 4-O(4-O-D-Galactopyranosyl) -D-Galatopyranosyl-D-Glucopyranose, and N' Diacetylchitobiose inhibited at moderate concentration (20mM). Conalbumin and ovoalbumin, also inhibited hemagglutination.