A cysticercus antigen was purified from the membrane. It is a glycoprotein containing hexoses and sialic acids with a molecular weight of 70 Kd and isoelectric focussing point 4.8. In western blot studies, the purified antigen bound with antibodies present in cerebrospinal fluid of all neurocysticercosis patients tested. Amino acid composition of the antigen showed a high content of Glutamate, Leucine and Aspartate while Proline and Hydroxyproline were absent. When cysts recovered from pigs were cultured for eight days, the excretory-secretory antigen obtained bound strongly with the antibody raised against the purified antigen. This indicates the homology of the two antigens. The possibilities of using this antigen for vaccination are discussed.