Two antigens (190 and 230 kDa) of the larvae of Taenia solium were detected in the cerebrospinal fluid (CSF) of 14 of 18 patients in which neurocysticercosis was suspected. Nine of these were confirmed by histopathology. Seven antigens were detected in cyst fluid of T. solium larvae removed from the brains of 6 infected patients. Two of these antigens had the same Mr as the T. solium antigens detected in the CSF. Polyacrylamide gel electrophoresis and electro-immunoblotting analyses were used for the identification and characterization. Antibodies in rabbit anti-larval antiserum and antibodies in sera of infected individuals recognized the same larval antigens in the larval cyst fluids and in the CSF of infected patients.