Spurious polycythemia is not a primary disease process. It sometimes may be nothing more than an unusual, but normal, physiologic state. In other instances, however, it is associated with a true abnormality of plasma volume. Although there is probably overlap between these extremes, differentiation of these subclasses may be of prognostic significance. The elevation in hematocrit bears no relation to morbidity, and, because there is no evidence of abnormal erythroid proliferation, reduction of red cell volume via phlebotomy or myelosuppression is inappropriate. Nonhematologic parameters, particularly hypertension, are the major factors of significance in the substantial cardiovascular morbidity in spurious polycythemia, and they demand attentive and aggressive management.