1. The transport of water, sodium and chloride across the jejunal mucosa was studied in fourteen patients with untreated adult coeliac disease by using a triple-lumen tube perfusion system. The results were compared with those obtained by identical methods in fifteen normal control volunteers.
2. Evidence was obtained suggesting that not only was absorption impaired in the adult coeliac disease group, but that in some patients there was secretion of water and electrolytes.
3. No significant improvement had occurred in six patients 2–4 months after withdrawal of gluten, nor in one patient after 8 months, in spite of histological improvement and clinical remission.