The clinical efficacy and safety of ibopamine and diuretic therapy were compared in a multicenter, multinational, parallel, positive-controlled, randomized, double-blind, 12-week study, involving 103 patients with mild CHF (NYHA Class II). Body weight, NYHA functional class, symptom assessment scores, laboratory blood tests, and exercise testing were evaluated at baseline at interim visits and at the end of 12 weeks. Clinical events were monitored throughout the study. There was no difference in any of the considered parameters between the two patient groups at baseline and at the end of the 12-week evaluation. A trend of improvement in clinical conditions that did not reach statistical significance was noted in each group throughout the study, as a probably "trial effect." Five patients on ibopamine had severe clinical events leading to drug discontinuation (CHF worsening, ventricular tachycardia, elevation of liver transaminases, headache, gastrointestinal disorders) and five on diuretic therapy experienced serious side effects (skin rash, palpitation, atrial fibrillation, elevation of liver transaminases, manic episode). One patient died while on diuretic therapy. Only headache and skin rash were considered to be related to the therapy (ibopamine and diuretic therapy, respectively). Our trial suggests that ibopamine can be safely and effectively used as an alternative for diuretics for up to 3 months in patients with mild CHF.