Human hemoglobin (Hb) and Hb cross-linked between the alpha subunits with bis(3,5-dibromosalicyl)fumarate (alpha alpha Hb) were used to treat hemorrhagic shock in water-deprived swine. Water was withheld for 48 h to induce a 10% loss of body mass, and 25 ml/kg of blood were removed in 1 h to produce circulatory shock. Swine were resuscitated with 1) Hb, 2) alpha alpha Hb, 3) human serum albumin, or 4) Ringer lactate. Mild high-output renal failure was observed in the non-cross-linked Hb-treated animals but not in other groups of animals. Swine treated with Hb and alpha alpha Hb had increases in plasma creatine kinase and lactate dehydrogenase activity that were resolved within 7 days. Both Hb- and alpha alpha Hb-treated swine displayed marked elevations of mean blood pressure in the systemic (39 +/- 6 Torr) and pulmonary (20 +/- 6 Torr) circulations that continued for 3 h and were associated with reduced cardiac output and a doubling of the systemic and pulmonary vascular resistances. Oxygen delivery was equivalent, and the rate of correction of the lactic acidosis was equal in all groups.