A case of Schistosoma mansoni infection in a 28 year old male after allogeneic bone marrow transplantation presenting with portal hypertension and gross hematuria is described. Schistosomiasis was confirmed by the discovery of parasites in the feces, together with the failure the patient to respond to multiple antimicrobial and antifungal treatment. After praziquantel administration, toxic or septic shock syndrome evolved and the patients died of acute renal failure on day 39 post-transplant. In this report, we would like to emphasize the importance of pre-transplant stool and urine cultures, and appropriate serologic tests in patients coming from endemic areas. Patients diagnosed with schistosomiasis must be treated at least 3 to 7 weeks before transplantation.