An immunoenzymologic (Elisa) serodiagnosis of cysticercosis is evaluated in 75 encephalic cysticercotic patients whose diagnosis of the disease and its progression is assessed by tomodensitometry. A Taenia solium antigen is used. Only Ig G are investigated. The sensibility of serodiagnosis is 85 % and specificity 87 % when there is a progression of the disease; no difference is noticed in the patients without any progression of the disease and in control normal subjects. This serodiagnosis of cysticercosis appears of value for the evaluation of the activity of the disease.