1. The effects of CGS 9896, a partial benzodiazepine agonist, and chlordiazepoxide, a full benzodiazepine agonist, on stress-induced gastric ulcers as well as blood glucose were compared. 2. Ulceration in the glandular stomach was induced by 2 h restraint at 4 degrees C. 3. CGS 9896 reduced significantly the ulcer parameters but did not affect blood glucose. The effect of CGS 9896 was dose-dependently blocked by the benzodiazepine antagonist flumazepil. 4. Chlordiazepoxide reduced the ulcer parameters but increased blood glucose. 5. Since CGS 9896 lacks sedative effects but reduced ulcer parameters, the anti-ulcer and sedative effects of drugs acting at benzodiazepine receptors are disassociated. 6. Benzodiazepine-induced hyperglycaemia does not play a major role in the anti-ulcer effects.