Cancer and its treatment launch many attacks on megakaryocyte and plat
elet production. This article focuses on the hematopoietic cytokines t
hat affect this process. Frier to the cloning of thrombopoietin, at le
ast two of these cytokines, IL-11 and PIXY 321, displayed promising cl
inical effects. To determine how these agents will compare to the phys
iologic regulator of platelet production will require carefully contro
lled clinical trials. The next few years most certainly will see the r
esolution of many of the complications of thrombocytopenia.