Intravascular volmes were sequentially determined in 13 African children recovering from protein-calorie malnutrition. The red cell volume was measured by a radiochromium technique; the total blood volume and the plasma volume were calculated. The absolute volumes were related to body size and were compared with the control values. Before treatment, the total blood volume was low per unit of body size, the red cell volume was more reduced than the plasma volume. On the 20th realimentation day, the absolute red cell volume had increased less than the absolute plasma volume, the total blood volume was almost normal per unti of body size. On the 60th realimentation day, near recovery, the absolute red cell volume had again increased, but again less than the absolute plasma volume, and the venous hematocrit was lower than on admission; the total blood volume was normalized per unit of body size, the red cell volume was low with a supranormal plasma volume. The rehabilitation period was characterized by an aggravation of the hemodilution already present before treatment. The significance of the changes in volemia per unit of body size was unclear because of the changing body composition.