In an open investigation, ciramadol, a partial agonist of opioid, was found to be a potent analgesic when 20 mg was given intravenously to 30 patients experiencing severe pain of renal colic. Total pain relief was obtained in 9 patients, while very good pain relief was obtained in 17 others. However, severe pain was experienced again in 7 of them after 1 to 2 hours. Vomiting and nausea occurred in 9 patients, and dizziness was present in 7 patients. The haemodynamic equilibrium was not changed by the analgesic.