To compare the tolerance and the cost of three replacement fluids in plasmapheresis: albumin 4% alone, albumin 4% + dextran 40, or albumin 4% + hydroxyethylstarch 6%.A one center randomized, cross-over, comparative study designed to explore the tolerance and the colloid oncotic pressure in patients undergoing plasmapheresis.225 plasmapheresis procedures were performed in 27 patients.Hemodynamic tolerance was good in the three treatment groups. Serum protein concentration after plasmapheresis was significantly lower in the albumin + hydroxyethylstarch group, followed by albumin + dextran 40, versus albumin alone. Colloid oncotic pressure before and after exchange was similar in the three groups.The clinical use of 25-30% of hydroxyethylstarch 6% or dextran 40 with albumin 4% was clinically well tolerated and associated with a 12% decrease of the cost of substitution solutions.