Decapeptide ceruletide (CRL), chemically related to cholecystokinin and gastrin, proved to have remarkable analgesic properties when administered to a group of 22 burned patients, 15 patients with acute myocardial infarction, and 8 patients suffering from pain caused by malignant tumours with metastases. Its effect was such, that many of the patients required no other analgesics (opiates) even after a prolonged administration (up to 10 days) of CRL. In some of the patients a marked euphoria developed. There were no substantial changes in EEG records during CRL administration in 15 controls, among them 4 epileptics. It is probable that CRL helps to activate the internal analgesic system. In the burned patients cortisol, testosterone, renin, prolactin and tri-iodothyronine (T3) levels in serum (plasma) were measured (radio-immunoassays). CRL did not block the stress response (no drop of increased cortisol levels, no increase in low T3 levels), but it modified (influenced) it (drop of the high renin levels, and a tendency to increase the very low testosterone levels). CRL appears to act as an endorphin releaser, as evidenced by the plasma levels of beta-endorphins (quotations). CRL and similar drugs may represent a new, more physiological and probably safer approach to the management of pain.