Thirty-six infants suffering from gastrointestinal diseases during infancy were evaluated for exocrine pancreatic function by means of the pancreozymin-secretin test. Duodenal fluid volume, protein content, and content and peak-specific activity of amylase, lipase, and trypsin were determined following intravenous administration of either pancreozymin (CCK) or secretin. Seven infants receiving long-term parenteral nutrition and 17 infants receiving oral feedings and exhibiting first-degree malnutrition in association with chronic diarrhea underwent testing. Results were compared to those of a group of 12 age-matched infants with chronic diarrhea and weight loss. Four patients receiving total parenteral nutrition (TPN) suffered from severe short bowel syndrome and three had intractable diarrhea of infancy. The total duration of TPN ranged from 1.5-12 months, and the period of exclusive TPN in the absence of oral feedings ranged from 1-4 months. The heights, weights, and weight-for-height relationships were at or above the fifth percentile for all seven infants. The weight-for-height relationship of each patient in the control group was above the fifth percentile, while that of all malnourished infants was below the fifth percentile. No significant difference was found in the volume of fluid collected following either CCK or secretin administration. The content and concentration of amylase and lipase were lower in those patients receiving TPN. The levels were statistically significant (p less than 0.05) following secretin administration. In contrast, the peak-specific activity and total trypsin content, as well as protein content, was not significantly different in patients receiving TPN, controls, and malnourished patients.(ABSTRACT TRUNCATED AT 250 WORDS)