TTP is a disease with protean manifestations leading to errors in diagnosis. Critical reevaluation of a single observer's experience at LIJMC over a 7-year period is compared to that in published literature. We retrospectively analyzed presentation, clinical course, treatment, and outcome of 15 patients treated for TTP between 1990 and 1997 by one of the authors (V.C.). Minimal diagnostic criteria for TTP were unexplained moderate to severe thrombocytopenia (platelet count <100,000/cmm), microangiopathic hemolytic anemia, with or without low grade fever, and no other attributable etiologies. Neurologic and/or renal dysfunction constituted severe grade. Age range was 5-86 years, with one patient age 5, the youngest yet to date reported with classic TTP. Female to male ratio was 2:1. Overall survival rate was 87%; 40% of patients experienced immediate relapse within the first 4 weeks of presentation; and predisposing causes for immediate relapse appear to be intercurrent infections and severity of presentation. There was a 40% incidence of late relapses of TTP. Two patients with an unusually high number of late recurrences (6 and 16) were HCV-Ab positive and the possible role of persistent HCV infection in recurrent TTP was explored.