In order to investigate further the reported beneficial effect of deglycyrrhizinated liquorice in gastric ulcer, a trial with a double-blind, cross-over design was performed. The patients were treated during two consecutive periods of four weeks each with either liquorice extract during the first period and placebo during the second or placebo during the first period and liquorice during the second. Only patients with chronic ulcer disease were accepted for the trial. The dosage of the liquorice extract was 760 mg three times daily. During the first period 38 patients with 47 ulcers in the ventricle and during the second period 30 patients with 36 ulcers took part in the trial. The patients' sex, age, site of the ulcer in the ventricle, and ulcer size in the groups treated with liquorice and placebo during periods I and II were similar. Nor could any difference be shown between the groups treated with liquorice and placebo with respect to heredity, duration of ulcer disease, alcohol consumption, smoking, or the use of drugs. There was no tendency to quicker healing in either group as regards change of ulcer area or complete healing. Small ulcers healed more quickly than big ones. Ulcers at the angulus healed very poorly. No side effects of treatment were observed.Our study was not able to demonstrate any healing effect of the liquorice extract (Caved-S) on gastric ulcer.