The effect of prednisolone on the adapted ileum of the rat after jejunal resection was examined. Three weeks after 50% proximal small bowel resection animals were fed pharmacological doses of soluble prednisolone (0.75 mg/kg/day) over a one week period, and killed at four weeks. Animals treated with prednisolone showed significant increases in brush border alpha-glucosidase, leucyl-2-napththylamidase and gamma-glutamyl transferase (P less than 0.01) per unit length of intestine compared with resection alone and transection reanastomosis control groups. This increase was the result of a significant enhancement (P less than 0.01) of brush border digestive enzyme activity per milligram of epithelial cell DNA-that is, per enterocyte-and was associated with a similar increase in enterocyte RNA content. In contrast, the activities of lysosomal and mitochondrial marker enzymes per milligran of DNA were similar in each group. Cell proliferation was not further stimulated by prednisolone. Thus prednisolone can selectively enhance brush border digestive capacity after intestinal resection without increasing cell proliferation. The increase in enterocyte RNA suggests that enzyme induction may be the mechanism of this effect.