A simple and sensitive technique, enzyme-linked immunosorbent assay (ELISA) was used for the quantitation of secretory IgA (sIgA) in order to study the synthesis and transport of sIgA in the nasal secretion from patients with chronic sinusitis. Rough-surface glass beads coated with antisecretory component antibody were employed as the solid phase. The minimal detectable concentration of sIgA was 50 ng/ml in this study. sIgA averaged 226.3 +/- 217.4 mg/dl and total IgA averaged 302.0 +/- 137.5 mg/dl.