Summary. Blood volume changes have been measured in 65 patients with splenomegaly due to a miscellany of causes. The red‐cell mass is often normal despite the fact that anaemia is present, and the anaemia is in part due to sequestration of red cells in a splenic pool and haemodilution of the red cells in an expanded plasma volume. Both factors may be relieved by splenectomy although the ultimate prognosis is dependent on the primary disease present.

SYNOPSIS Platelet survival has been measured in 16 patients with idiopathic thrombocytopenic purpura. Of this group, three patients had a normal result and surface counting did not show high spienic uptake. The clinical features of these patients are described. These patients have remained well for several years without treatment.