Two patients with CsA-associated neurotoxicity developed severe cerebellar swelling and thrombotic thrombocytopenic purpura after switching to FK506 and high-dose corticosteroids. The prodrome of CsA-associated neurotoxicity, TTP and hypertension while receiving FK506, and high-dose corticosteroids could all be implicated in the development of this syndrome. Close monitoring of patients receiving FK506 and high-dose corticosteroids, for the development of TTP is warranted. Early radiological examination should also be considered in such patients to allow early surgical intervention.