SummaryA relationship between disaccharidase and diamine oxidase (DAO) activities was looked for by measuring these enzyme activities in histologically normal small intestinal biopsies of 18 children. The range for disaccharidase activities expressed in U g-1wet weight was 0.1-5.7, 7.1-36.7, and 2.3-8.5 for lactase, maltase, and sucrase, respectively. The range for DAO activities expressed in nmol h-1g-1wet weight was 202-974. Significant correlations were found between disaccharidase and DAO activities (lactase versus DAO: n=17, r=0.80, P<0.001; maltase versus DAO: n=18, r=0.70, P<0.001; sucrase versus DAO: n=18, r=0.55, P<0.05). Our results further support the hypothesis that DAO is a marker of small intestinal functional integrity in children.