We describe the case of a 57-year-old woman with chronic myelogenous leukemia who was on hydroxyurea and developed a fatal thrombotic microangiopathy with renal, retinal and central nervous system involvement. There was no evidence of medullary or extramedullary leukemia transformation. Repeated examinations of the peripheral blood film revealed only minimal morphological changes of microangiopathic hemolysis. The diagnosis was made by postmortem examination of the kidneys, brain, meninges and retina. The underlying etiology may have been a paraneoplastic phenomenon of the chronic phase of CML or may have indicated the beginning of transformation to an accelerated phase. A late side effect of hydroxyurea therapy cannot be excluded.