The solubility of 1per thousand dispersions of freeze-dried (FD) and commercial spray-dried (sd) (containing less than 0.1per thousand SDS) egg white protein (EWP) was determined in water and in 0.1, 0.3, and 0.5M NaCl and NaI, and 0.01, 0.05, and 0.1M Na₄P₂O₇ at pH 3, 5, 7, and 9. Protein solubility generally increased at higher pH and salt concentrations over the ranges studied. Both I and P₂O₇ ions, but not Cl, substantially increased the apparent solubility of FDEW, but had less effect upon the solubility of SDEW. Both NaI and Na₄P₂O₇ changed the character of the solvent in a way similar to that of SDS, a known protein denaturant and solubilising agent. The effect of these two salts upon EWP solubility was more pronounced than for bovine serum albumin.