The histological distribution of receptors for the lectins Wheat germ (WGA). Ricinus communis I (RCA I) and Soybean (SBA) was examined in ameloblastomas and normal oral mucosa from 12 patients. The study utilized fluorescein-conjugated WGA, RCA I and SBA. Cell-membrane bound receptors for these 3 lectins were demonstrated in the spinous cell layer of the normal oral mucosa. WGA and RCA I receptors were also located in the basal cell layer, whereas SBA receptors were not detectable there. Cell-membrane bound WGA receptors were shown in the epithelial cells of the ameloblastomas. Titrations showed significant differences in staining reactivity related to the morphology of the peripheral epithelial cells of the ameloblastomas. The distribution of RCA I and SBA receptors in the peripheral cells was also related to the morphology of these cells and was independent of the histological types of the tumours. It is suggested that the distribution of these receptors is related to cellular activities such as cell differentiation and cell migration in the tumour and therefore possibly reflects the biological behavior of the tumours.