The role of the ariginine-metabolism in the healing action of the Piper betle phenol, allylpyrocatechol (APC) and omeprazole against indomethacin-induced stomach ulceration in mouse was investigated. Indomethacin (18 mg/kg) was found to induce maximum stomach ulceration in Swiss albino mice on the 3rd day of its administration, which was associated with reduced arginase activity (21.6%, P<0.05), endothelial nitric oxide synthase (eNOS) expression (72%, P<0.001), and IL-4 and TGF-beta levels, along with increased inducible nitric oxide synthase (iNOS) (9.3 folds, P<0.001) expression, nitrite (2.29 folds, P<0.001), IL-1beta and IL-6 generation. Besides providing comparable healing as omeprazole (3 mg/kg x 3 days), APC (5 mg/kg x 3 days) shifted the iNOS/NO axis to the arginase/polyamine axis as revealed from the increased arginase activity (73.1%, P<0.001), eNOS expression (67.8%, P<0.001), and reduced iNOS expression (65.6%, P<0.001) and nitrite level (53.2%, P<0.001). These can be attributed to a favourable anti-/pro-inflammatory cytokines ratio, generated by APC. The healing by omeprazole was however, not significantly associated with those parameters.