Lung transplantation is limited by a shortage of suitable lung donors. Fluid loading is widely used to increase blood pressure during donor maintenance. In a prospective study, we investigated the effect of fluid loading with lactated Ringers solution on pulmonary function in 26 brain-dead adult organ donors. In all patients, the initial central venous pressure (CVP) was <6 mmHg. In 13 patients, a CVP of 8–10 mmHg was achieved and maintained for 90 min by an infusion of lactated Ringers solution. This resulted in a significant increase (P<0.05) in the alveolar arterial oxygen gradient. In 13 patients, the CVP was maintained at 4–6 mmHg for 90 min by, if necessary, an infusion of lactated Ringers solution. In these patients, no significant change in the alveolar arterial oxygen gradient occurred. Pulmonary gas exchange has been shown to be a reliable means of evaluating donor lung function. We conclude that crystalloid fluid loading to a CVP of 8–10 mmHg may be deleterious to lung function and should be avoided in potential lung donors.