This research was aimed at investigating the ameliorative effect of Andrographis paniculata (AP) following indomethacin-induced gastric ulcer. A total of 20 male albino Wistar rats (150-180g) used for this study were grouped into four (n=5): Normal Control, Negative Control, induced with gastric ulcer using indomethacin at 20mg/kg but untreated; Positive Control, induced with gastric ulcer and treated with omeprazole at 20mg/kg; Test Group, induced with gastric ulcer and treated with aqueous extract of AP at a dose of 16.7mg/kg. Body weight changes of the animals were measured every three days while water and food intake were measured daily. After the treatment protocol, the animals were used for estimation of ulcer parameters. The LD50 value of aqueous extract of AP was 50mg/kg (bw). Water intake was significantly reduced in omeprazole treated group compared to control and ulcer untreated groups but significantly increased in AP treated group. Body weight change was significantly reduced in omeprazole treated group compared to all other groups while extract treated group significantly increased body weight change. Gastric acid secretion was significantly reduced in the treated groups when compared to the ulcer untreated group. Gastric mucus was significantly increased in omeprazole and AP groups compared to ulcer untreated and control groups. Pepsin was significantly increased in ulcer untreated group compared to control. However, omeprazole and AP significantly reduced pepsin compared to ulcer untreated group. Pepsin was also significantly reduced in AP group compared to omeprazole group. Cross sectional macroscopic examination of the gastric mucosa in ulcer untreated group showed two or more haemorrhagic ulcers while this effect was seen to be ameliorated in omeprazole and AP treated groups. From the result of this study, AP has proved to be more potent in protecting against peptic ulcer disease than omeprazole. If this result is applicable to humans, the use of AP in ameliorating the debilitating consequences of peptic ulcer should be researched and encouraged.