The aim of this study was to determine whether there is an association between dengue infection and intestinal mucosal injury. Serum levels of intestinal fatty acid binding protein (I-FABP) were used as a specific marker for mucosal injury. The diagnosis of all patients was serologically confirmed by anti-dengue IgG or IgM. Serum I-FABP levels of 120 patients were determined and compared to those of 25 controls using ELISA. In order to investigate serum I-FABP among dengue patients, they were categorized into 5 groups according to disease severity: dengue fever (DF), dengue hemorrhagic fever (DHF) grade I through DHF grade IV. The dengue patients had higher levels of serum I-FABP compared to 25 controls (408.0 +/- 499.3 vs 124.72 +/- 147.81 pg/ml, p=0.006). The patients with DHF grade IV had the highest levels of serum I-FABP, ALT, and AST compared to the other groups. However, there were no differences in serum I-FABP, ALT, and AST levels among patients with DF, DHF grade I, grade II, and grade III. Evidence of intestinal mucosal injury in patients with dengue infection was demonstrated. Patients with DHF grade IV had high serum I-FABP levels and had associated liver injury.