As part of a screening program for the occurrence of lectins in leguminous plants [1, 2] we have found a lectin in seeds of viciu ervilia, which we have purified and partially characterized. The serological specificity of extracts from seeds of this species was reported earlier [3-51. The compound was isolated directly from a raw extract of I/. ervilia seeds by specific adsorption to a D-mannose-substituted Sepharose gel and subsequently desorbed with a glucose solution. The material recovered from a second adsorption-desorption treatment was found to be homogeneous on ultracentrifugation and free zone electrophoresis although with a pH-dependent tendency for aggregation. Its mol. wt of 60 000 may be accounted for by four subunits which are identical pairwise with molecular weights of 21 000 and 4700, respectively. The lectin molecule lacks carbohydrate and furthermore lacks sulphur containing amino acids and is rich in acidic and hydroxylic amino acids, which are usual features of this class of molecules [6-91.