At the ultrastructural level, the Caenorhabditis elegans (Maupas, 1900; Doughert, 1953) cuticle shows the presence of six layers: epicuticle, external cortical, internal cortical, intermediate, fibrous and basal. Two techniques were used for carbohydrate localization: the periodic acid-thiosemicarbazide-silver proteinate (Thiéry) and gold-labelled lectins. No labelling was found on the nematode's cuticle. With the ethanolic phosphotungstic acid technique (E-PTA), that detects basic proteins, reaction product was observed in the outer cortical layer, in the cuticle struts and in the dense bodies of the muscle cell. Surface anionic sites of C. elegans were visualized by using cationized ferritin particles, at pH 7.2, and by using colloidal iron hydroxide particles at pH 1.8. Treatments with trypsin and neuraminidase (Vibrio cholerae) did not interfere with the binding of the cationic particles to the nematode's surface. In contrast, treatment with chondroitinase ABC, a specific enzyme for glycosaminoglycans, significantly reduced the binding.