Fluorescein conjugated lectins have been used as histochemical stains in lymph node sections from 22 patients with non-Hodgkin's Lymphoma. Variations in the distribution and structure of glycoprotein sequences between the different types of lymphoma, and also normal nodes, have been detected. The lectin-binding patterns of neoplastic lymphocytes of small cell lymphomas, both follicular and diffuse, suggested a predominance of sialylated glycopeptides, as in normal small lymphocytes of the mantle zone of germinal centres. In contrast, the staining patterns of large cell follicular and diffuse lymphomas showed a greater diversity of carbohydrate structure, with enhanced cytoplasmic staining and increased numbers of incomplete oligosaccharide sequences. Heterogeneity of staining, together with reduced sialic acid expression at all cellular sites was a common feature of lymphoblastic lymphomas and seemed to be linked with a poor prognosis. The extracellular matrix of small cell follicular lymphomas showed altered saccharide content, but retained some degree of organization. The large cell follicular lymphomas were characterized by a prominent disorderly matrix, with staining characteristics which suggested shedding of surface membrane from component cells. The loss or disordered production of the normal extracellular matrix may reflect a breakdown of control mechanisms within neoplastic follicles.