Sclero-atrophic lichen (LSA) is a dermatosis that is well defined from the clinical and histological viewpoints, but the etiology remains unknown. The main symptom is a permanent pruritus which results in a gynecological consultation. We have studied the immunological status of 48 patients with LSA and 33 controls. The LSA patients showed a significant diminution of peripheral CD3 and CD1 and tissue CD2, CD3, CD1 and CD8. There was no difference of IgG, IgM or tissue C3c, or serum C3c and C4. These patients also had a higher incidence of autoantibodies.