This study evaluated the acid-base and metabolic effects of several organic anions which might have application in the correction of metabolic acidosis during hemodialysis. Anesthetized dogs were infused intravenously with the sodium salts of either chloride, bicarbonate, acetate, lactate, or pyruvate. Acetate perturbated metabolism more than any of the other organic anions infused. These perturbations included hypoxemia, reductions in serum potassium and phosphorus, a decrease in plasma, glucose, and increases in intermediary metabolites such as lactate, acetoacetate and beta-hydroxybutyrate. Transferance of our findings to hemodialysis suggests that acetate would compromise the ability of dialysis to reduce body burdens of potassium and phosphorus and provide proper base repletion. Pyruvate would appear superior to acetate as a base substitute by virtue of its lesser effects on oxygen consumption and electrolyte distribution and its capacity to produce glucose. However, the significant production of lactate with pyruvate infusion, coupled with diffusive losses of bicarbonate during dialysis and the possible instability of pyruvate in solution, would still hinder proper base repletion. Bicarbonate generation with lactate infusion was too slow to provide a practical alternative for base repletion in hemodialysis. Bicarbonate infusion caused minimal alterations in intermediary metabolism. This, in conjunction with obviating diffusive losses, suggests the use of bicarbonate would allow more appropriate base repletion during hemodialysis.