Abstract: Nigella sativa, seeds has been used in traditional medicine for the treatment of a variety of diseases including gastrointestinal disorders. N. sativa seed powder (NS), its extracts and purified fractions were studied for their possible gastroprotective effects in the indomethacin-treated rats (adult albino male rats weighing 180-220 g) to rationalize the folkloric uses. NS protected the rats against indomethacin-induced gastric effects in a dose-dependent manner. The ethanolic extract of the powder (NS-E) also attenuated the indomethacin-induced changes in gastric juice volume, pH, acid-output and ulcer index. Partition of ethanol soluble ingredients in organic solvents yielded semi-purified fractions whose anti-ulcer activity guided further chemical purification. The active fraction w as chromatographically characterized and the most purified fraction (NS-EA 51) obtained, presented anti-ulcerogenic activities in indomethacin-induced gastric ulcers in the rats. Various parameters including gastric juice volume, pH, acid-output, ulcer index and peptic activity showed that it was the most potent anti-ulcerogenic fraction which gave results comparable to Famotidine. The gastroprotective or anti-secretary, anti-peptic and anti-ulcerogenic actions of NS-EA 51 might be related to its anti-inflammatory and/or antioxidant activity.