We investigated the effects of clinically appropriate doses of NaHCO3 on tissue oxygenation when hemorrhagic shock was corrected with hydroxyethyl starch (hetastarch) in 12 piglets. Six animals received colloid only while six received colloid and bicarbonate. Both groups recovered rapidly hemodynamically, but conjunctival, subcutaneous, and liver tissue PO2 values returned to baseline more slowly after bicarbonate administration. In the NaHCO3 group, pulmonary artery wedge pressure and arterial bicarbonate concentration were higher during early resuscitation, and arterial plasma lactate remained higher than in the control group at the end of the follow-up period. The delayed increase in tissue PO2 values after bicarbonate infusion may be explained, at least partly, by decreased arterial blood oxygenation and a shift of the oxyhemoglobin curve to the left. NaHCO3 adjunct has no added beneficial effect on hemodynamics and may be harmful to tissue oxygenation in hemorrhagic shock resuscitated with hetastarch.