Exocrine pancreatic function was evaluated in 19 diabetic children on the basis of a pancreozymin-secretin test, a p-aminobenzoic acid (PABA) test, and a determination of fasting plasma trypsin and elastase-1 levels. In the pancreozymin-secretin test, the diabetics exhibited lower mean values in all the parameters measured, significant differences being seen in the volume of duodenal fluid and the output of bicarbonate and amylase. Compared to the controls, the diabetics also had lower levels in the PABA test and in the trypsin and elastase-1 measurements. No significant correlation was seen between exocrine pancreatic dysfunction and the duration of diabetes. However, the duration of diabetes in children who showed extremely low levels (below the mean +/- 2 SD for the control subjects) in the PABA test and low plasma trypsin and elastase-1 values was more than 1 year. This study revealed that diabetic children had reduced exocrine pancreatic function, some in an early stage of the disease. Therefore, the reduction may be due to a functional disturbance rather than to an anatomical loss of exocrine pancreatic tissue.