This double-blind parallel-group study aimed to evaluate, by endoscopic examination, the reaction of the gastric mucosa to 7-day oral administration of nimesulide 100 or 200mg twice daily. Placebo was administered as a reference compound. 30 dyspeptic patients, randomly allocated to 1 of the 3 treatment groups, completed the study. On completion of treatment, 1 patient in each nimesulide dosage group and 2 in the control group showed evidence of gastric injury: 1 patient with slight hyperaemic gastropathy at baseline developed superficial ulcerations after treatment with nimesulide 100mg, and 1 patient with a history of gastric ulcer developed a congested corpus mucosa with several erosions and ulcerations after treatment with nimesulide 200mg; in the placebo group, 1 patient developed hyperaemic antropathy and another patient developed several petechiae and microerosions. The incidence of adverse effects was comparable in all groups and treatment was not associated with any significant modification of the considered haematological and haematochemical parameters.