Lectins are proteins able to create specific bounds with polysaccharides, such as those of the blood cells walls. Contained in many edible plants, including pulses, lectins have a toxicity to be evaluated. The quantification of these molecules rests on the exploitation of their haemagglutinating power on blood cells. The so-called haemagglutination method consists in extracting the lectins from the seeds fooled by a contact with blood cells. The determination of the concentration threshold from which hemagglutination is observed allow to determine the lectin concentration of the sample and express the result by a comparison with a purified lectin of reference.