1. During preservation of human plasma in the liquid state at room temperature for three years, the alpha-amino nitrogen and the nitrogen content of the tungstic acid filtrate rise slowly until about two years have elapsed, after which time these levels do not increase significantly.

2. During the entire period of storage the nitrogen contents of the trichlor-acetic acid filtrate and the "polypeptide index" increase progressively. The actual increase represents hydrolysis to nonprotein size of 3 to 4 per cent of the original protein.

3. The colloid osmotic pressure of stored plasma is slightly but significantly greater than that of fresh plasma.

4. The viscosity of stored plasma is slightly but significantly greater than that of fresh plasma.

5. The electrophoretic patterns of stored plasma show increases of alpha globulin and albumin concentration, complete disappearance of gamma globulin (containing immune properties) and fibrinogen, and some reduction of beta globulin concentration as compared to fresh plasma.

6. Analysis of 3,384 questionnaires completed after administration of liquid plasma more than a year old indicates that the transfusion of such plasma continues to be safe and beneficial up to at least three years of storage. The untoward reaction rate following these administrations was significantly less than that following a comparable series of 1500 administrations of commercially prepared dried plasma.

The technical assistance of R. L. Erickson, PhM1c, V6, U.S.N.R., and P. Livingood, PhM3c, V6, U.S.N.R., is gratefully acknowledged. The kindness of Dr. Ellice McDonald, Director, Biochemical Research Foundation, in arranging for the electrophoretic work and in permitting the reporting of the work here is appreciated with deep thanks. This study was possible only with the close cooperation of the Blood and Plasma Department, Naval Medical School. For this cooperation, the authors are considerably indebted to Commander S. T. Gibson, M.C., U.S.N.R., Lieutenant Commander H. R. Evans, (HC), U.S.N., and Lieutenant Commander M. T. Sproul, H(W), U.S.N.R.