Hereditary or congenital (TTP) is a very rare form of TTP which is associated with repeated attacks of TTP. I report a case of a 33-year old man who had had numerous attacks of TTP since birth and had evidence of mild chronic TTP between acute attacks. He had recurrent attacks despite immunosuppressive therapy, IV immunoglobuline and splenectomy. He has remained under clinical and laboratory control with regular infusion of 750 ml of cryopoor plasma every two weeks. Case history: JS, born in1972, exhibited severe neonatal jaundice associated with intravascular hemolysis and thrombocytopenia on the second day of his life. He was discharged on the 8th day with a final diagnosis of hemolytic uremic syndrome (HUS). In the first 8 years of life, he had 10 admissions to the Children’s Hospital with the diagnosis of HUS or TTP. He had been variously treated, with IV fluids, prednisone, aspirin, dipyridamole, antibiotics, and heparin + phenoxybenzamine. He had recovered from acute attacks; but, in between admissions, he had several less severe attacks of thrombocytopenis and/or hemolysis which did not require hospitalization. Between the ages of 8–17 he had had several other acute attacks of HUS for which he was generally admitted to other hospitals and treated with prednisone. He was first admitted to St. Boniface General Hospital (SBGH) in April 1992 with laboratory evidence of TTP [hemoglobin (Hgb) 95 G/L, platelet count (Plt) 17 x 10e9/L, urea = 11 mmol/L, creatinine 183 μmol/L and lactate dehydrogenase 683U/L]. He was treated with prednisone + enteric coated aspirin (ECASA) + dipyridamole and recovered from acute attacks and discharged after 5 days but he was readmitted 10 days later with another attack of TTP associated with decreased level of consciousness and left sided weakness. He responded to repeated plasmapheresis + prednisone + ECASA + dipyridamole and recovered completely. By the end of 1993, he had had 5 hospital admissions to SBGH for recurrent acute attacks of TTP and was successfully treated with repeated plasmapheresis + prednisone + ECASA. However between acute attacks he had shown evidence of mild thrombocytopenia and hemolysis. Preventive treatments with ECASA, ticlopedine, azathioprine and IV immunoglobuline had failed to prevent chronic TTP and acute attacks. In May, 1994, he underwent splenectomy for his chronic TTP, but 2 months later he had another episode of acute TTP. He was treated with plasmapheresis, prednisone and ECASA and responded well. He was then placed on regular infusion of 500 ml of cryopoor plasma (CPP) every two weeks as well as ECASA 325 mg daily. On this regimen, his Hgb, Plt and reticulocyte count remained normal. In August 1994, infusion of CPP was discontinued in order to find out whether the hematological improvement was due to the delayed effect of splenectomy or CPP infusion. Three months later he had another acute attack of TTP and he was treated with an infusion of 1500 ml of CPP daily for 4 days + prednisone and ECASA. He recovered completely. Infusions of 500 ml CPP every 2 weeks was restarted and he remained well until May 2, 1996 when he experienced another episode of acute TTP a day after he had undergone a tooth extraction. He was treated as he had been treated in the last attack with infusions of CPP and responded well. In the past 9 years he has received 750 ml of CPP infusion every two weeks and has remained in complete remission with normal platelet count, hemoglobin, reticulocyte count and haptoglonbin and he has not had any more acute attack of TTP.