110 patients with benign gastric ulcer and concomitant joint diseases (rheumatoid arthritis, osteoarthrosis) were treated in a comparative short-term clinical trial to assess the relative efficacy of calcitonin (daily 100 MRC of salmon calcitonin intramuscularly), cimetidine (daily 1000 mg orally) and colloidal bismuth subcitrate (De-Nol-four times a day in doses of 5 ml diluted with 15 ml of water). Groups of patients were comparable according to age, sex, duration of ulcer disease, smoking habits, gastric acid secretion and mean ulcer size. The ulcer healing was controlled endoscopically after 2 and 4 weeks of the treatment. There was no significant difference in the ulcer healing rate between three groups neither after 2 weeks (calcitonin-36.7% of healed ulcers, cimetidine-37.5% and De-Nol-35.0% nor after 4 weeks respectively (76.7%, 72.5% and 77.5%). In the calcitonin group a gradual joint pain relief was observed in 84% of patients who complained arthralgia. The moderate side effects (headache, nausea, flush) were observed only in the patients treated with calcitonin (8 subjects). We suggest that calcitonin may be considered as a valid anti-ulcer drug in the peptic ulcer patients with concomitant rheumatological diseases especially with osteoporosis.