Bone marrow transplant-associated thrombotic microangiopathy (BMT-TM), usually associated with thrombocytopenia, microangiopathic haemolytic anaemia (MAHA) and renal insufficiency, has been reported to occur approximately 5-6 months after BMT. We report a case of relapsed malignant lymphoma complicated by BMT-TM of hyperacute onset, which has never been described in the literature. Our patient, a 52-year-old male, developed MAHA with gross haematuria, thrombocytopenia, lactate dehydrogenase elevation and renal insufficiency 2 days after autologous PBSC transplantation following high-dose chemotherapy. Supportive treatment, ie glucocorticoid, fresh frozen plasma and haemodiafiltration were given, and thereafter the BMT-TM gradually improved. In heavily pretreated patients, caution should be exercised for possible occurrence of the BMT-TM of hyperacute onset.