Steroids and cytostatic drugs have an undoubtedly damaging action on the gastroduodenal mucosa. The action of pirenzepine was compared with that of the placebo in preventing the gastroduodenal lesions brought on by antiblastic therapy. Sixty patients were separated into two random group under double blind conditions and received 100 mg/die/os of pirenzepine or equivalent placebo for a continuous period of 12 weeks. Antiblastic drugs were administered at the same time. Final endoscopic control and symptomatological findings showed a statistically significant different in favour of the pirenzepine-treated group as early as the 6th week of treatment. No side-effects attributable to pirenzepine were reported.