Anagrelide, a selective thrombocytopenic agent, is administered to treat a variety of hematologic disorders. Despite limited clinical experience with this drug, serious cardiovascular events, including congestive heart failure, have been reported. The proposed mechanism of cardiotoxicity is attributed to inhibition of phosphodiesterase, resulting in positive inotropic activity and vasodilation. A 48-year-old woman with polycythemia vera developed cardiotoxicity manifested by congestive heart failure and palpitations. It was suspected to be temporally related to titrating dosages of anagrelide.