Peroral jejunal biopsies were performed in both clinically asymptomatic parents of 15 children with c.s. Histological, histochemical and biochemical exanimation revealed various alterations in 24 parents. Irregular configuration of villi, increased quantity of cytoplasmic RNA in enterocytes and decreased activities of membrane enzymes, shift of LDH-monomers in favor of the H-form and a decrease of total activity of lactase and cellobiase were found. The origin of changes, particularly their relation to the ingestion of gluten or to other injuries of the jejunal mucosa as well as to some hereditary mechanism, remains unknown at the present time.