This research was aimed to investigate anti-inflammatory effects of Aloe vera on leukocyte-endothelium in the gastric microcirculation of Helicobacter pylori (H. pylori)-infected rats. Thirty-six male Sprague-Dawley rats were divided into 3 groups: control, H. pylori-infected, and A. vera-treated group (200 mg/kg b.w., twice daily). H. pylori-inoculation was induced in the rats by the administration of H. pylori solution. Intravital fluorescence videomicroscopy was used to examine leukocyte adhesion in postcapillary venules on the posterior surface of stomach area on different periods after administration of A. vera. Serum tumor necrosis factor-alpha (TNF-alpha) level was measured in blood collected at the end of experiment by using ELISA technique. The results showed that in H. pylori-infected group on day 8, the leukocyte adhesion was 13.40+/-1.00 cells/100 microm vessel length and the TNF-alpha was 76.76+/-23.18 pg/ml, which increased significantly (p < 0.05), compared with the control group (leukocyte adhesion(control) = 2.54+/-0.6 cells/100 microm vessel length and TNF-alpha(control) = 9.92+/-2.62 pg/ml). Treatment with A. vera reduced the leukocyte adhesion (5.5+/-0.5 cells/100 microm vessel length), and TNF-alpha (26.31+/-6.38 pg/ml) significantly (p < 0.05). In conclusion, H. pylori enhanced leukocyte-endothelium interaction in the posterior stomach area markedly. This enhancement in leukocyte-endothelium interaction could be improved by the treatment of A. vera, associated with reduction in TNF-alpha level.