An experiment was conducted to the effect of dietary phytic acid (PA) and phytase supplementation on small intestinal histomorphologyand Na-dependent glucose transporter 1 (SGLT1)gene expression in piglets. Twenty-four piglets with anaverage initial BW of 7.60 ± 0.73 kg were randomlyassigned to 3 experimental diets, to give 8 piglets perdiet. The diets were a casein-cornstarch-based diet thatwas supplemented with 0 or 2% PA, or 2% PA (asNa phytate) plus an Escherichia coli-derived phytaseat 500 phytase units/kg. The basal diet was formulatedto meet the 1998 NRC energy, digestible AA, mineral,and vitamin requirements for piglets. After 10 dof feeding, the piglets were killed to determine smallintestinal histomorphology and small intestinal SGLT1gene expression. Phytic acid supplementation did notaffect (P > 0.1) villus height (VH) and the VH-to-cryptdepth (CD) ratio, but did decrease (P < 0.05) CD inthe jejunum. Phytase supplementation did not affect (P> 0.1) VH, CD, and the VH-to-CD ratio. Phytic acidsupplementation reduced SGLT1 gene expression in theduodenum, jejunum, and ileum by 1.1-, 5.4-, and 2.4-fold, respectively. Phytase supplementation increasedSGLT1 gene expression in the jejunum by 2.6-fold,but reduced SGLT1 gene expression in the duodenumand ileum by 2.0- and 4.0-fold, respectively. In conclusion,PA reduced CD in the jejunum and SGLT1gene expression in the duodenum, jejunum, and ileum,whereas phytase supplementation increased the expressionof SGLT1 in the jejunum. The reduced SGLT1gene expression by PA implies that PA reduces nutrientutilization in pigs partly through reduced expression ofSGLT1, which is involved in glucose and Na absorption.The increased expression of SGLT1 in the jejunum byphytase supplementation implies that phytase alleviatedthe negative effects of PA partly through increasedexpression of SGLT1. © 2011 American Society of Animal Science. All rights reserved.