Background: Thrombotic thrombocytopenic purpura [TTP] whether idiopathic or secondary is a rare but life threatening disease.We describe the clinical spectrum and response to treatment and explore the risks for relapse in our cohort of patients.Study Design and Methodology: patients treated for TTP at the Clinical Hematology Unit of the Department of Internal Medicine of Cairo University between 2000 and 2008 were identified.Results: A total of 30 patients;13 males (43%) and 17 females (57%) with a median age of 42 years were treated for 46 episodes of TTP.The median duration of disease onset-to-diagnosis for the first episode was 7 days with 11 patients (37%) presenting with coma.Disease related mortality: Three patients (10%) died from their initial disease: One drug-induced patient (cyclosporine),two idiopathic patients (heavily platelet transfused prior to their late admission 9 & 10 days from onset of symptoms) died during the first 24 hours.A fourth patient died 48 hours after the initiation of the third Px session from multiple cerebral infarctions.Upon follow-up, two patients died: an HCV positive patient from complications in the context of splenectomy and a second patient with refractory disease from progressive neurological deficiency.Patterns of response to plasmapharesis: Twenty two patients (85.6%) achieved remission with an average of 7.55 Px sessions, 13 of whom achieved a sustained remission (50%) with an average of 6 Px whereas 4 patients (15.3%) were defined as refractory.Another 9 patients had 25 relapses (mean 2.7) with an average of 9 Px sessions to achieve remissions.Additional therapies used with plasmapharesis:Overall survival: The 24 months overall survival was therefore 80%.When stratifying survival, excluding first 24 hour mortality of very lately referred cases the survival would be 24 out of 27 (88.8%).Secondary TTP survival was (85.7%).Factors associated with relapse: The only statistically significant differences between the two groups were in platelet count and LDH levels (P value < 0.05).There was no correlation between use of Azathioprine or other immunosuppressants and relapse (r-0.39, P=0.12)ADAMTS-13 was reduced in 10 patients (83.3%) and antibodies recoverable in 9 out of 12 patients (75%).No correlation between it and the clinical parameters or relapse.Conclusions: The current results are conforming to the reported literature of the outcome of TTP.The very early mortality due to late referral highlights the need of education and awareness about the disease among primary health care providers.