Abstract[2‐(Diethylamino)ethyl]dextran hydrochloride (EA) was reacted with a mixture of sodium dextran sulfate (DS) and poly(styrene sulfonate) (NaSS) to form a novel water‐water precipitate, a so‐so polyelectrolyte complex (PEC), comprising three biomedical materials. The mole ratios of (DS + NaSS)/EA in PEC's prepared at higher [H+] were greater than at lower [H+] except for those PEC's prepared in 5% NaOH solution. IR, elemental analyses, solubility measurements, and blood clotting tests for PEC's revealed that the molecular structure of the various PEC's differed according to the [H+], order of mixing in solution, though all PEC's were prepared from the same starting materials. It appears that the degree of dissociation and the conformation of DS, NaSS, and EA change with [H+] and that a different neutralization reaction occured in terms of different order of mixing. Blood clotting tests were performed on PEC tablets. It was found that PEC's suppressed the coagulation of blood compared with