The aqueous suspension of Commiphora molmol (oleo-gum resin) has been screened for its potential to protect gastric mucosa against the ulcers caused by 80% ethanol, 25% NaCl, 0.2 M NaOH, indomethacin and combined indomethacin-ethanol treatment. C. molmol pretreatment at doses of 250, 500 and 1000 mg/kg provided dose-dependent protection against the ulcerogenic effects of different necrotizing agents used. The effects caused by ethanol were further investigated. Treatment of rats with 1 ml of 80% ethanol was found to cause depletion of stomach wall mucus, reduction in the concentration of protein, nucleic acids and NP-SH groups in the stomach wall. Ethanol treatment also caused histopathological lesions including necrosis, erosion, congestion and haemorrhage of the stomach wall. Pretreatment with C. molmol offered a dose-dependent protection against all these effects. In the same manner it affected the malondialdehyde concentration altered by ethanol treatment. C. molmol also offered protection against mucosal damage caused by indomethacin and its combination with ethanol. The protective effect of C. molmol observed in the present study is attributed to its effect on mucus production, increase in nucleic acid and non-protein sulfhydryl concentration, which appears to be mediated through its free radical-scavenging, thyroid-stimulating and prostaglandin-inducing properties.