The aim of this study was to determine the secretion of secretory immunoglobulins and gliadin antibodies in the small bowel in celiac disease. Twenty-four patients were investigated by perfusion of a defined jejunal segment. Four of the patients studied had a serum IgA deficiency and had no measurable amounts of secretory IgA in the perfusion fluid. The other patients demonstrated a significant increase in the jejunal concentration of secretory IgA (median 28.5 mg/liter) compared with healthy controls (median 16 mg/liter, N = 16) and of IgM, celiac (median 12.3 mg/liter) compared to healthy controls (median 6.8 mg/liter, N = 16). Jejunal IgA gliadin antibodies were detected in all patients except those with an IgA deficiency. All patients had jejunal IgM gliadin antibodies, but none of the patients had measurable jejunal IgG gliadin antibodies. A positive correlation was detected between serum and jejunal IgA gliadin antibody levels in the celiac patients, (P less than 0.01). Calculation of the ratio between gliadin antibodies and total levels of IgA and IgM in serum and jejunal perfusate demonstrated that the jejunal synthesis of gliadin antibodies of IgA and IgM type is both more pronounced and persistent than the systemic humoral immune response to gliadin.