Abstract: 120 1-day-old parental male Arbor Acre (AA) broilers were randomly divided into 4 replicates, respectively. Regional expression of sodium hydrogen exchanger 2 (NHE2) mRNA in different intestinal tract segments of AA broiler at 30-day-old and ontogenetic expression of NHE2 mRNA in duodenum and jejunum of AA broilers were determined by relative quantitative RT-PCR. It was found that: (1) Expression of NHE2 mRNA in duodenum, jejunum, ileum and colorectum was declined. The abundance of NHE2 mRNA in duodenum and jejunum was higher than that in ileum and colorectum (P<0.05)，respectively. (2)Ontogenetic patterns of NHE2 mRNA were same between duodenum and jejunum. The abundance of NHE2 mRNA was increased from 2- to 16-day-old, decreased from 30- to 44-old-day and increased again on 58-day-old. The abundance of NHE2 mRNA on 16- and 30-day-old were higher than that on 2-, 44- and 58-day-old (P<0.05)，respectively. These results indicate that regional expression of NHE2 mRNA in intestine of AA broilers was significantly declined along the downward intestine from proximal intestine to distal intestine (P<0.05). Ontogeny of NHE2 mRNA in AA broilers had the same pattern in duodenum and jejunum, indicating that NHE2 mRNA expression could be regulated by developmental stage.