Summary
Studies of blood volume in the rat following treatment with large doses of cytotoxic drugs revealed that significant depletion of red cell volume followed the use of cyclophos‐phamide and nitrogen mustard and, to a lesser extent, methotrexate. The anaemia in the case of nitrogen mustard is not revealed by haemoglobin or haematocrit studies, it being masked by hypovolemia following use of the drug. The results indicate that red cells as well as white cells are at risk in cancer chemotherapy.