Background:Very few studies have been reported on the expression of human pancreatic genes during fetal development. We have shown very low lipase immunoreactivity compared with elevated trypsinogen immunoreactivity in a previous immunohistological study of human fetal pancreas during development.Methods:The expression of these two selectively expressed genes of the exocrine pancreas, trypsinogen and lipase were investigated. The developmental profiles of the corresponding mRNA's were determined from the 13th gestational week.Results:For the two genes, fetal mRNA levels throughout gestation remained significantly lower than the corresponding adult levels. No correlation was found between trypsinogen and lipase gene expression in the fetal pancreas, whereas such a correlation was present in adult pancreas. This may be explained by differences in maturity of the pancreas.