The effect of pneumonectomy in dogs on extravascular lung water (EVLW) was studied using a double-indicator (iced indocyanine green dye) dilution technique. The EVLW was measured in five dogs before and after a left pneumonectomy while left atrial pressure was increased in 5-mm Hg increments from 10 to 25 mm Hg by serially inflating a left atrial Foley balloon. There were no significant differences in hematocrit, total protein, or plasma oncotic pressure before or after pneumonectomy. Prepneumonectomy EVLW was adjusted to reflect right lung EVLW alone. Both before and after pneumonectomy there was a significant increase in EVLW when left atrial pressure was increased to 25 mm Hg. However, EVLW values were similar before and after pneumonectomy at each level of left atrial pressure. We conclude that pneumonectomy does not acutely increase susceptibility to EVLW formation caused by a hemodynamic challenge. This implies that following pneumonectomy, if left heart filling pressures are normal, there is no clinical benefit to excessive fluid restriction.