When administered orally Ibopamine, the diisobutyric ester of N-methyldopamine, has pharmacological properties similar to intravenous dopamine: in particular, both renal blood flow and the urinary excretion of sodium and water increase. The drug also enhances creatinine clearance, both in normal subjects and in patients with impaired renal function. Twenty-eight patients affected with chronic renal insufficiency were treated with oral Ibopamine (100 mg/day) for 4-56 weeks. They were divided into 2 groups according to whether the creatinine clearance was more or less than 15 ml/min: Group 1 contained 21 patients (mean clearance 29.09 ml/min) and Group 2 7 patients (mean clearance 8.42 ml/min). Ibopamine treatment was ineffective in Group 2, while in Group 1 patients there was a statistically significant increase in creatinine clearance (+23% after 3 months, +31% after 6 months). Drug tolerance was excellent from both clinical and laboratory points of view.