We have studied the effects of ibopamine, an oral dopamine derivative, on pulmonary hemodynamics and blood gas values when given as a single oral dose (100 mg) to patients with severe hypoxic chronic obstructive pulmonary disease. A small but significant increase in mean pulmonary arterial pressure from 29 ± 8 to 32 ± 7 mm Hg (p < 0.01) was noted 30min after ibopamine was given associated with a small increase in cardiac index. No other consistent hemodynamic changes were observed, and no alteration in blood gas values or oxygen saturation occurred. These results do not indicate a role for ibopamine in the treatment of patients with hypoxic chronic obstructive pulmonary disease and pulmonary hypertension, but, in addition, do not indicate any major deleterious effects of ibopamine on pulmonary hemodynamics or blood gas values in such patients.