The L-fucose-binding lectins present in the seeds of Ulex europaeus and Lotus tetragonolobus have been isolated by affinity chromatography. The binding specificities of the lectins were compared by hemagglutination inhibition analysis. The lectins behaved similarly with respect to a variety of synthetic saccharides. D-Fucose derivatives were inactive as inhibitors. In general, the alpha -L-fucopyranosyl derivatives were better inhibitors than the beta-L-fucopyranosyl derivatives. Aromatic aglycones increased the inhibitory activity of the saccharides with p-nitrophenyl-alpha-L-fucopyranoside being one of the best inhibitors. The major difference between the two lectins was the observation that the Ulex lectin required higher concentrations of saccharides to bring about complete inhibition of hemagglutination than did the Lotus lectin.