With disodium hydrophosphate (DHP) solution of various concentrations (0.1-0. 6g/100mL) as preservative for erythrocyte mass, the changes were found in erythtocyte count (ERc), pH and osmosis of those from National Institute of Hematology and blood trasfusion during a storage period of 42 days: gradual decreases in ERc and pH but decreases in osmosis. DHP (0.2-0.6g/100mL) showed its ability to maintain ERc, stabilize pH and osmosis of the erythrocyte mass, but after 42 days' storage the ERc, pH and osmosis just remained 32 percent, 6.81 and 345mOsmol/Kg, respectively. Formulation 02 (with 0.2g/100mL of DHP) was selected for further studies in combination with other storage factors.