Long term pirenzepine treatment of duodenal ulcer patients was carried out. Full dose pirenzepine therapy (100 mg/day) for 28 days resulted in 34 (77%) out of 44 duodenal ulcer patients with endoscopically healed lesions. Sixteen of them, randomly chosen, were treated with low pirenzepine doses (50 mg/day) for 6 months with evidence of clinical and endoscopic ulcer relapse in 3 cases (18.7%); while in 16 subjects who interrupted the treatment completely, evidence of clinical recurrence in 11 (68.7%) and of endoscopic recurrence in 10 (62.5%) within the following six months. The statistical analysis failed to reveal significant differences between treated and not treated patients. These data were compared with what observed after interruption of treatment in 16 patients whose duodenal ulcer previously healed after 28 days of antacid therapy. Clinical ulcer recurrence in up to 6 months were shown in 9 (56.2%) of them, and endoscopic relapses were shown in 7 (43.7%). In conclusion, the maintenance therapy with low doses of pirenzepine reduces the number of ulcer relapses when compared with pirenzepine withdrawal or with antacid withdrawal, even though this difference is not statistically significant.