Controlled mechanical ventilation (CMV) with positive and expiratory pressure (PEEP) is often used to improve the pulmonary gas exchange in patients with acute respiratory distress syndrome. However, this ventilatory technique may induce hemodynamic and hormonal changes which may lead to vital organ dysfunction, such as oliguria. Low dose dopamine, acting as a dopaminergic receptor agonist, may improve vital organ perfusions, i.e. renal, mesenteric and coronary perfusions. The purpose of this current study was to evaluate the effects of low dose dopamine on renal function and hemodynamic change during controlled mechanical ventilation with PEEP. The study was performed on 10 patients treated with PEEP in the surgical intensive care unit. Starting with 0 cmH₂O of PEEP and adding 4 cmH₂O of PEEP at 4-hour intervals until it reached 12 cmH₂O of PEEP, dopamine, 2 ug/kg/min, was selectively, administered, intravenously during the last two hours of each four hour intervals. Following each procedure, hemodynamic parameters, urine output, creatinine clearance and fractional excretion of sodium were measured. The cardiac index and mean arterial pressure had both decreased, but the mean pulmonary arterial pressure was increased at 12 cmH₂O of PEEP compared with 0 cmH₂O of PEEP in both groups with and without low dose dopamine. The main result of this study was that low dose dopamine attenuated the decrease of the cardiac index, urine output and creatinine clearance induced by mechanical ventilation with PEEP at 12 cmH₂O.