The chloride content of red cells suspended in KC1 solns. at pH 7.6 was fairly constant within wide limits of dilution. HC1 entered the red cells when they were in a soln. of glucose, HC1, and KC1; and as the concn. of KC1 increased, more HC1 entered the cell. The phosphate-chloride equilibrium was unstable since on standing more phosphate entered the cell and Cl was displaced.