This study investigated intestinal physiology of piglets at weaning. Piglets (n = 60) weaned at 21 d were food deprived for 2 d and then tube-fed using 2 different diets (a conventional diet vs. a wheat-enriched diet). They were slaughtered at d 0, 2, 5, 8, or 15 postweaning. Jejunum, ileum, and colon were mounted in Ussing chambers. In addition, segments of the proximal jejunum of 4 growing pigs were studied 35 d after weaning. Secretory function was assessed by basal short-circuit current (Isc) and secretagogue-stimulated Isc. Glucose absorption was measured by the increase in Isc after the addition of glucose. Epithelial barrier function was measured by transmucosal resistance (R) and horseradish peroxidase (HRP) fluxes across the epithelium. There were no significant differences between the pigs fed the 2 diets for any of the parameters studied. As already reported, a transient villous atrophy was observed. At the same time, we observed an increased basal Isc in jejunum and colon, increased glucose absorption and a dramatic drop of R in jejunum. These parameters had returned to preweaning values by d 5. Weaning was also followed by long-lasting modifications. In jejunum, responses to the secretagogues and glucose absorption were decreased at wk 2 after weaning and were not different between d 15 and 35. Ileal transmucosal resistance increased on d 5 and was stable thereafter. HRP flux in jejunum declined on d 2 and stayed at this low level throughout the experiment. We conclude that weaning induces transient dramatic changes in intestinal physiology but is also a period of maturation of the intestine. J. Nutr. 134: 2256–2262, 2004.